Random take...
ESTps have a need to be involved with people even though they may not always be able to fulfill this need. Anyways they can't just be in a group of people without trying to get involved and get somekind of important role there. If they can't get that role they probably leave. ISTps are more likely to be a bit "enigmatic". They don't make much contact but they are rather friendly if you contact them. And often they can hang around with group of people without making much effort to get involved. Just kind of observing the situation. ESTps are kind of energetic bunnies which sometimes can dragon breath on you if they dislike you. ISTps are more like enigmatic beings which suddenly open up and then close down again. ESTps are more likely to engage in discussions and analyze things. ISTps rarely seem to analyze. They just state their opinion which is pretty non-negotiable. They may change it later when they are alone but during the discussion they just have a tendency to voice their opinion and that's it. ESTps are more interested in forcing their opinions on you however. ISTps tend to ignore you if you disagree with them. ESTps tend to get agitated if you disagree with them. If you have problems ISTps are more likely to be empathetic and caring although usually not by words. ESTps seem to dislike people with problems and distance themselves from them. ESTps seek constant fun and excitement and people with problems generally are the opposite of that. ESTp has extremely short attention span and they will immediately switch to doing something else if you start to bore them (this is true for ISTp too in some sense but still it is very different from the "jumpy" nature of ESTp). Just give ISTp good food and they will be happy to listen to you while eating. ESTp is way more needy and hard to please.
ESTp has this "hunter" aura where ISTp is more enigmatic and has "I'm independent" aura.
ESTp might look like this:
Where ISTp might look like this: