From my experience, though, the ESTP emulation in social situations held true when I was somewhat immature, and even then it was not 100% so.
The reason being, (apologies in advance to some), ESTPs bullsh*t far too much for an ENTJ tolerance level. After a while, you realize that their social success is often built on very shaky foundations, and it does not fit the ENTJ preference for self-congruence, authenticity and general 'solidness'.
Cheat sheet - how do you distinguish between an ENTJ and ESTP?
1. ESTPs have a signature attribute: they are 'always on the go'. Sometimes annoyingly so. Some will even rock on their toes, stand sideways, in a 'walking away' posture, tap their feet, play with their cellphones etc. WHILE interacting with you. They strongly believe in the maxim 'he who travels fastest, travels alone'. ENTJs, on the other hand, once committed, will be intensively engaged.
2. ESTPs are extremely interested in leveraging themselves through people in the SHORT term. ENTJs, are also interested in leveraging themselves through people, but in the LONG term - which is why we focus a lot more on aligning incentives and team building. Loyalty matters to them, and they are loyal themselves. ESTPs, on the other hand, are much more focussed on looking out for #1, especially in the here and now.
3. ESTP (guys) are more 'slick' and charming on 1st impressions. Both ENTJs and ESTPs can come across as cocky, but the ENTJ will prefer to be cocky only if he believes he has earned it. The ESTP on the other hand, is the 'Promoter', and his world revolves around convincing the world about how amazing his life is. Most people believe him, at least initially.
4. ESTPs are much more hot blooded than ENTJs.
5. Both ESTPs and ENTJs are generally very sharp, but ESTPs are better in tactical situations, and ENTJs are better in strategic situations.
6. ESTPs are likely to be significantly better at sports than ENTJs.
7. ESTPs find it much easier to have fun than ENTJs, and probably are more fun.