I know that some people get confused about how we arrive at the subtypes, so I'll explain them. Consider the ENTp-Ti subtype and the INTj-Ne subtype:
(Victor Gulenko) Self-centred and pensive. Their ideas do not have direct connection with reality, for example philosophy, religion, bioenergetics etc. Their favourite occupation is comparing different logical systems. A type of office scientist. A very slim figure is characteristic for them. Angular in their movements, does not pay attention to external appearance, worry little about their health.
(Victor Gulenko) Analyst; a good scientist and conceptualist. Their primary attention is given to global issues. A generator of ideas. Achievements with potential are more important to them than the result of the current moment. Soft, correct and careful in his social contacts. Outwardly frequently very slim, gives more attention to external appearance and health than Logical subtype.
What you'll notice about these two subtypes is how they are very similar. It might even be possible to switch around the descriptions, and things would not be that inconsistent. What's going on here is that the subtypes form a relationship similar to this grouping:
If you consider the subtypes as being on sort of a spectrum, the ENTp-Ne and INTj-Ti subtypes are right next to each other. That means that there is a fine line separating these two types. That fine line is equivalent to an equal amount of Ne and Ti - a type completely between the ENTp and INTj. So, basically, the subtypes are determined by the amount of emphasis placed on the primary and secondary functions. In an INTj, when the amount of Ne used is close to the amount of Ti used, you get an INTj-Ne. When the amount of Ti used far surpasses the amount of Ne, you get an INTj-Ti. The reason the ENTp-Ti and INTj-Ne are so close in description is because both types are close in the amount of Ne and Ti that they use. This leads to two types that are nearing equal use of Ne and Ti, so they seem very similar. Both of those descriptions fit me so well, that I have discovered that I'm one of those two types. Choosing which one I fit is like splitting hairs, so you might as well flip a coin.