INTP's are indirectly more outward than ENTP's. We're basicly like ENTP's but don't want to put other people through that ordeal by toning down our ENTPness.
I only know one ENTP in real life, my brother, he's an unhealthy ENTP type. Makes up tons of stories, exegerates loads, and often seems to believe himself no matter if he's obviously wrong or not. All the while being completely incapable to reach out a helping hand. He isn't all that stupid, but he sometimes sure does appear that way.
Luckily he got me to go INTP anger on his ass every now and then, keeps him in check a little bit.