Uh I think ENFPs being the most introverted is a fallacy, I say ENTJ! Te doesn't really see the need to socialize unless it fits the agenda, to which they use Se for that.
Unless of course the ENTJ is on an Se binge, then they'll be loud ESFPs
Let's see. IMO ESFP/ENFP aren't really different because Se/Ne are very similar in the sense they they are very random and are generally reactive to outside stimuli. However Se makes a reaction based on what's happening now (random) while Ne makes a reaction based on connections that are received from the outside stimuli (random also).
1) ENFPs are dominant intuition, being N dom and an extrovert is somewhat of an oxymoron as intuition, even Ne, is an inevitably introspective function. when you combine that with the reflective, withdrawn function that is Fi, you get a pretty introverted extrovert.
2) Ne and Se are not as similar as you think. explain MBTI to any ENFP who plays sports and they will probably say something along the lines of "oh! that's why I'm so clumbsy and terrible with details" among other things
3) Te is about directing the outside world, depending on the situation, it is often extremely extroverted, just more poised than say Fe.
4) Ne deals with hypothetical connections, scenarios, ideas and metaphors. none of these things are tangible or present in the outside world
5) several ENFPs on this forum test regularly as introverts but don't realize they're ENFP until they study function theory. for most types, if you're stuck on if you're E or I, you're probably I. for NFPs, if you're stuck between E and I, you are vastly more likely to be ENFP.
6) I am an ENFP and I need several hours a day to myself to recharge. several ENFPs I've talked to say this is the same for them. a few other types of extroverts will say this on occassion, but only ENFPs say this consistantly
7) ENFPs' extroversion is over estimated because they're trait extroversion (big 5 extroversion) is usually extremely high.