Gay vs lesbian relationships--are they different?

it is really difficult to see the difference between the two except for the fact that in the first one, it involves two males and, the second one involves two females. most of us will find it difficult to understand what made them decide to proceed with a relationship like that when they cannot have children that way. i have heard that men who do not want to have children in their relationships take gays for their partners. if this is true, then it is easy to see the reasoning behind the relationship. i don't know if this holds true to the lesbian relationships, too.