Well let's think about the differences for a second.
INTP
Dominant Introverted Thinking
Auxiliary Extraverted Intuition
Tertiary E/I Sensing
Inferior Extraverted Feeling
ENTP
Dominant Extraverted Intuition
Auxiliary Introverted Thinking
Tertiary E/I Feeling
Inferior Introverted Sensing
Our area of confidence is our ability to process information that we take in and make clear objective decisions. ENTPs use that same function, but as their area of creativity instead. Where we take some information and do massive amounts of analysis, they take massive amounts of information and do some analysis. It gives direction to their ideas. The observe more of the world, but I believe we realize more about what we observe.
Our auxiliary extraverted intuition is our area of creativity. We have to see the patterns to do our analysis and we enjoy finding patterns, but an ENTP sees all the patterns, not just in their area of interest. If you want ideas, they are the ones you want because they will see more of the unique perspectives than anyone else.
Extraverted feeling is our achilles heel, being something we have trouble controlling, that can control us, but ENTPs don't have that trouble. It isn't one of their primary strengths, but they're likely to find things like small talk to be a reasonable diversion.
Introverted Sensing is where it can get interesting for an ENTP. Just like how we can be the ultimate non-emotional people but fall prey to our feeling and lose control, ENTPs are masters of fighting the status quo, but find themselves suffering defeat at the hands of their inferior introverted sensing, that strongly desires that structure and authority.
I just put that together, so it might not all be right, but I think it draws the comparisons pretty well. One letter can make an awful lot of difference.