Personally I think it is how you feel in yourself. Some are happy when dressed 'en femme' presenting themselves to world as female/male but on a part time basis, some are in the process of transitioning and want be their desired gender. Others, well for them it's a fetish, a means of experiencing a 'sexual high'. However, Society does likes labels.
Personally I've never really been a fan of labels. If you want to call yourselves a crossdresser, transvestite, transgender or a Drag Queen/King or Bob! Then really it's up to you, if it makes you happy. Happiness is what's inside, not what's on the label.
And that concludes today's table top philosophy