A lot of people are of the opinion that an MBTI INTJ is a socionics INTp and vice versa. Let's find it out by analyzing the descriptions in detail...

Quote Originally Posted by personalitypage INTJ
INTJs live in the world of ideas and strategic planning. They value intelligence, knowledge, and competence, and typically have high standards in these regards, which they continuously strive to fulfill. To a somewhat lesser extent, they have similar expectations of others.
Ideas are an Alpha-NT domain. INTj is strategic wheras INTp is tactical.
1:0

Quote Originally Posted by personalitypage INTJ
With Introverted Intuition dominating their personality, INTJs focus their energy on observing the world, and generating ideas and possibilities. Their mind constantly gathers information and makes associations about it. They are tremendously insightful and usually are very quick to understand new ideas. However, their primary interest is not understanding a concept, but rather applying that concept in a useful way. Unlike the INTP, they do not follow an idea as far as they possibly can, seeking only to understand it fully. INTJs are driven to come to conclusions about ideas. Their need for closure and organization usually requires that they take some action.
Confusing passage because they interpret Ni completely differently than in socionics. Again, ideas are INTj but applying instead of understanding concepts is INTp.
1:1

Quote Originally Posted by personalitypage INTJ
INTJ's tremendous value and need for systems and organization, combined with their natural insightfulness, makes them excellent scientists. An INTJ scientist gives a gift to society by putting their ideas into a useful form for others to follow. It is not easy for the INTJ to express their internal images, insights, and abstractions. The internal form of the INTJ's thoughts and concepts is highly individualized, and is not readily translatable into a form that others will understand. However, the INTJ is driven to translate their ideas into a plan or system that is usually readily explainable, rather than to do a direct translation of their thoughts. They usually don't see the value of a direct transaction, and will also have difficulty expressing their ideas, which are non-linear. However, their extreme respect of knowledge and intelligence will motivate them to explain themselves to another person who they feel is deserving of the effort.
INTj is harder to understand than INTp.
2:1

Quote Originally Posted by personalitypage INTJ
INTJs are natural leaders, although they usually choose to remain in the background until they see a real need to take over the lead. When they are in leadership roles, they are quite effective, because they are able to objectively see the reality of a situation, and are adaptable enough to change things which aren't working well. They are the supreme strategists - always scanning available ideas and concepts and weighing them against their current strategy, to plan for every conceivable contingency.
INTj is strategic, INTp is tactical.
3:1

Quote Originally Posted by personalitypage INTJ
INTJs spend a lot of time inside their own minds, and may have little interest in the other people's thoughts or feelings. Unless their Feeling side is developed, they may have problems giving other people the level of intimacy that is needed. Unless their Sensing side is developed, they may have a tendency to ignore details which are necessary for implementing their ideas.
Applies to both.
3.5:1.5

Quote Originally Posted by personalitypage INTJ
The INTJ's interest in dealing with the world is to make decisions, express judgments, and put everything that they encounter into an understandable and rational system. Consequently, they are quick to express judgments. Often they have very evolved intuitions, and are convinced that they are right about things. Unless they complement their intuitive understanding with a well-developed ability to express their insights, they may find themselves frequently misunderstood. In these cases, INTJs tend to blame misunderstandings on the limitations of the other party, rather than on their own difficulty in expressing themselves. This tendency may cause the INTJ to dismiss others input too quickly, and to become generally arrogant and elitist.
INTj is clearly more arrogant and harder to understand.
4.5:1.5

Quote Originally Posted by personalitypage INTJ
INTJs are ambitious, self-confident, deliberate, long-range thinkers. Many INTJs end up in engineering or scientific pursuits, although some find enough challenge within the business world in areas which involve organizing and strategic planning. They dislike messiness and inefficiency, and anything that is muddled or unclear. They value clarity and efficiency, and will put enormous amounts of energy and time into consolidating their insights into structured patterns.
Business and efficiency are INTp.
4.5:2.5

Quote Originally Posted by personalitypage INTJ
Other people may have a difficult time understanding an INTJ. They may see them as aloof and reserved. Indeed, the INTJ is not overly demonstrative of their affections, and is likely to not give as much praise or positive support as others may need or desire. That doesn't mean that he or she doesn't truly have affection or regard for others, they simply do not typically feel the need to express it. Others may falsely perceive the INTJ as being rigid and set in their ways. Nothing could be further from the truth, because the INTJ is committed to always finding the objective best strategy to implement their ideas. The INTJ is usually quite open to hearing an alternative way of doing something.
Hard to tell. Applies to both in a way.
5:3

Quote Originally Posted by personalitypage INTJ
When under a great deal of stress, the INTJ may become obsessed with mindless repetitive, Sensate activities, such as over-drinking. They may also tend to become absorbed with minutia and details that they would not normally consider important to their overall goal.
This point goes to the INTj who is Se-vulnerable, even though it might also apply to some INTps.
6:3

Quote Originally Posted by personalitypage INTJ
INTJs need to remember to express themselves sufficiently, so as to avoid difficulties with people misunderstandings. In the absence of properly developing their communication abilities, they may become abrupt and short with people, and isolationists.
Applies to both.
6.5:3.5

Quote Originally Posted by personalitypage INTJ
INTJs have a tremendous amount of ability to accomplish great things. They have insight into the Big Picture, and are driven to synthesize their concepts into solid plans of action. Their reasoning skills gives them the means to accomplish that. INTJs are most always highly competent people, and will not have a problem meeting their career or education goals. They have the capability to make great strides in these arenas. On a personal level, the INTJ who practices tolerances and puts effort into effectively communicating their insights to others has everything in his or her power to lead a rich and rewarding life.
Applies to both.
7:4

Conclusion
7:4 is not a very clear result but in my opinion it is rather a description of the type we know as Analyst in socionics.

Let's look at the INTP:

Quote Originally Posted by personalitypage INTp
INTPs live in the world of theoretical possibilities. They see everything in terms of how it could be improved, or what it could be turned into. They live primarily inside their own minds, having the ability to analyze difficult problems, identify patterns, and come up with logical explanations. They seek clarity in everything, and are therefore driven to build knowledge. They are the "absent-minded professors", who highly value intelligence and the ability to apply logic to theories to find solutions. They typically are so strongly driven to turn problems into logical explanations, that they live much of their lives within their own heads, and may not place as much importance or value on the external world. Their natural drive to turn theories into concrete understanding may turn into a feeling of personal responsibility to solve theoretical problems, and help society move towards a higher understanding.
Analyze problems, identify patterns, logical explanations. Clearly INTj.
0:1

Quote Originally Posted by personalitypage INTp
INTPs value knowledge above all else. Their minds are constantly working to generate new theories, or to prove or disprove existing theories. They approach problems and theories with enthusiasm and skepticism, ignoring existing rules and opinions and defining their own approach to the resolution. They seek patterns and logical explanations for anything that interests them. They're usually extremely bright, and able to be objectively critical in their analysis. They love new ideas, and become very excited over abstractions and theories. They love to discuss these concepts with others. They may seem "dreamy" and distant to others, because they spend a lot of time inside their minds musing over theories. They hate to work on routine things - they would much prefer to build complex theoretical solutions, and leave the implementation of the system to others. They are intensely interested in theory, and will put forth tremendous amounts of time and energy into finding a solution to a problem with has piqued their interest.
Generate theories, enthusiasm, ignoring rules, new ideas. Definitely INTj.
0:2

Quote Originally Posted by personalitypage INTp
INTPs do not like to lead or control people. They're very tolerant and flexible in most situations, unless one of their firmly held beliefs has been violated or challenged, in which case they may take a very rigid stance. The INTP is likely to be very shy when it comes to meeting new people. On the other hand, the INTP is very self-confident and gregarious around people they know well, or when discussing theories which they fully understand.
Depends on subtype.
0.5:2.5

Quote Originally Posted by personalitypage INTp
The INTP has no understanding or value for decisions made on the basis of personal subjectivity or feelings. They strive constantly to achieve logical conclusions to problems, and don't understand the importance or relevance of applying subjective emotional considerations to decisions. For this reason, INTPs are usually not in-tune with how people are feeling, and are not naturally well-equiped to meet the emotional needs of others.
Definitely INTp. Constructivist, objectivist and Fe-vulnerable. INTj is emotivist, subjectivist and Fe is his dual-seeking function.
1.5:2.5

Quote Originally Posted by personalitypage INTp
The INTP may have a problem with self-aggrandizement and social rebellion, which will interfere with their creative potential. Since their Feeling side is their least developed trait, the INTP may have difficulty giving the warmth and support that is sometimes necessary in intimate relationships. If the INTP doesn't realize the value of attending to other people's feelings, he or she may become overly critical and sarcastic with others. If the INTP is not able to find a place for themself which supports the use of their strongest abilities, they may become generally negative and cynical. If the INTP has not developed their Sensing side sufficiently, they may become unaware of their environment, and exhibit weakness in performing maintenance-type tasks, such as bill-paying and dressing appropriately.
Self-aggrandizement, social rebellion and creative potential are clearly INTj traits. The rest applies to both in a way so the point goes to the INTj.
1.5:3.5

Quote Originally Posted by personalitypage INTp
For the INTP, it is extremely important that ideas and facts are expressed correctly and succinctly. They are likely to express themselves in what they believe to be absolute truths. Sometimes, their well thought-out understanding of an idea is not easily understandable by others, but the INTP is not naturally likely to tailor the truth so as to explain it in an understandable way to others. The INTP may be prone to abandoning a project once they have figured it out, moving on to the next thing. It's important that the INTP place importance on expressing their developed theories in understandable ways. In the end, an amazing discovery means nothing if you are the only person who understands it.
Applies to both.
2:4

Quote Originally Posted by personalitypage INTp
The INTP is usually very independent, unconventional, and original. They are not likely to place much value on traditional goals such as popularity and security. They usually have complex characters, and may tend to be restless and temperamental. They are strongly ingenious, and have unconventional thought patterns which allows them to analyze ideas in new ways. Consequently, a lot of scientific breakthroughs in the world have been made by the INTP.
Unconventional instead of traditional. INTj.
2:5

Quote Originally Posted by personalitypage INTp
The INTP is at his best when he can work on his theories independently. When given an environment which supports his creative genius and possible eccentricity, the INTP can accomplish truly remarkable things. These are the pioneers of new thoughts in our society.
New thoughts are an Alpha domain. INTj.
2:6

Conclusion
The INTJ scored 7:4 and the INTP even 6:2 as INTj. So both are Analysts and not Critics, probably with different subtypes. Maybe the guys on personalitypage are going to write a description of the socionics INTp-Critic soon...