Why is the Vampire Diaries show different from the books?

I first started watching the shows, but now i am reading the books also. I think they're both great, but im kind've likeing the show better. I just don't like the fact that Stephan and Damon HATE each other soooo much. In the show they at least don't let anything happen to one another and get along. Does the hatred change later on in the book series because i've only read the first book. I'm alittle farther than halfway through it.