To me, the biggest Ne/Ni conflict is like this:
Ni: there are possible problems ahead! Prepare for them!
Ne: who says these problems will occur and not other ones? If there are any problems, we'll solve them on the spot. Now, what about *insert fun thing*?
I see the introverted perceiving functions as being of a more "judger" character, in the sense that they will help you to plan things; while the extraverted perceiving functions are the improvising on the spot ones.