Nothing other than gender and political pressure.
Absolutely nothing in terms of love and commitment.
Legally it is different because homosexual people are not legally allowed to get married in many states and/or countries.
At that same rate, marriage laws can differ all over the world legally as well as culturally.
Culture and social constructs in various places also recognize or does not recognize the validity of homosexual versus heterosexual marriage.
So round about answer, marriage laws and the legality of marriage experiences diversity all over the world. The commitment between two adults is essentially always between the two adults, regardless of gender, etc.
I don't think you can. You either has to be single or married to adopt. Just living together is neither. if you are in a samesex relationship and has gone through partnership might be possible though.
Anyone can do anything they want to as long as they truly want it. No, in Islam having a boyfriend/girlfriend type of relationship is not allowed whether your a male or a female and whether the bf/gf is Muslim or not. If you have anymore questions regarding the matter, just ask and I'll be happy to answer them. i gree in islam having a boyfrnd or a grlfrnd is not allowd but today no youngr generation follows it .....so if a muslim girl personlly like a non muslim boy...then it is not allowd in islam.....u cannot marry him unless he accpts islam...:)