The differences are really small and insigificant ones.

I have had a "boyfriend" now for coming on to four years.  I have found myself acting a lot  like a hetero, in regard to all the usual practices and issues of coupledom.  I was a bit surprised at myself but really only because of past societal misguidances regarding gay men which even I had believed to some extent. 

I now think men are men, whether gay or straight, and relate to promiscuity and monogamy in the same way.  Straight men have to deal with the feminine part of the equation, so the opportunities are a bit different. 

I still have reservations about marriage.  I think there should be equal rights (duh!), but I don't know about making and breaking promises.  I think marriage is dictated in part on religious beliefs (faulty religious believes if I need to point that out) and religion is such a mess.