Quote Originally Posted by whatever View Post
not to be blunt, but I always thought that system was oversimplified... there's a major difference in how my ISTJ and I use our Sensing and Thinking functions, despite the fact that we're both STs

I understand what you mean, i was quite confused by that at first.

A key thing to note, is that Jack's "N"/"S" are wholistic ("P") functions, whereas "T"/"F" are linear ("J"). Just think of Ne/Se/Te/Fe, they are fairly close to what he means by N/S/T/F.

So, when you are ESTP, you are quite different from an STJ since your primary is a wholistic S (similar to "Se") whereas their primary is a linear T (similar to "Te").