They are women, and womanhood lies between the ears, and not between the legs. And if they're post-op, their lovemaking is the same as that of any two women in love. One can be a man or a woman, and one can prefer a man or a woman. The two aren't related. Apples and oranges.
Gender is a sense of self.
Sylvia would occasionally express herself as a woman even if she were the last person on Earth, and so would Bette. Andrea and Samantha have become women, just as Brooke would like to become a man, because that is the way they have always seen themselves. Sharon is a special case. She's transgendered, but firmly imbedded in the gay community. She is always at the park on Pride Day, was bashed outside the Gallus and again at Ansley Mall, has a gay male lover, reads all the bar publications, and shops primarily at gay-owned businesses.