When you're obsessed with something, whether a thought or an action, you have little room for anything else. I have a friend with an Elvis obsession. He watches Elvis movies, tries to talk like him, has all the biographies ever written on him, has all his music, and even has coffee cups and sheets with Elvis's face. That's an obsession.
A compulsion is something you feel you have to do, but you don't necessarily want to do. If my Elvis friend suddenly jumps up on stage and tries to sing Kentucky Rain, that would be compulsive.
As lazysimpson said, obsessions are thoughts while compulsions are actions. Which is why we call it obsessive compulsive disorder. They tend to go together. Although I suppose you could be obsessive without doing anything about it.
Compulsive is when you feel the NEED to do something, there isnt a large difference. A complusion is an overwhelming erge to do the same thing over and over again.
obssessions are recurring thoughts while compulsiveness/compulsion are recurring actions..
Ummmm Stefie, please reread the question and the answer u gave, thx