Do you mean what is the difference between the terms "gender" and "sex"?
Because from my anthropology class I've learned that "sex" is that it is biologically founded, whereas "gender" is socially/culturally adapted.
I feel that 'sex' is what one biologically/physically is, whereas 'gender' refers to what they feel they are, mentally. It takes a lot of patience, an open-mind, and the ability to be completely comfortable with oneself to be considered gender
less. It's an interesting topic, though. How one can deviate, mentally, from what they biologically are.
A lot of people are brought up thinking that sex and gender are the same, but that also says a lot about how people initially felt about the topic. Traditional views on it are that gender matches corresponding one's biological sex, but in modern-culture, we realize how that isn't always the case. (eg, homosexuals, bisexuals, transsexuals.) It's interesting when a person is born one sex, but regards themselves as the opposite gender, using it as a lifestyle and identity. It sounds tough, and many people who harbor feelings like this suffer being given a body they might consider themselves inadequate, with or without an SRS. I have friends who have undergone SRSs and psychological distress from not being the gender they wished they were born with.
And from that, another topic. It isn't completely relevant, but you'll see the relation. In Plato's
Symposium, it was said that in ancient times that there were three types of people. Male/female, male/male, and female/female. Then God came along and split those people in half, and those people spent their lifetimes looking for their other half. The whole "the one" idea. Realistically, we know ideas like this aren't true... but it's romantic, isn't it?
With humans, we're able to accept our sexuality and have it apply to our everyday lives. Humans live under the circumstances where we are able to do, whereas had we been another animal instead, natural selection would've wiped most homosexuals out due to their inability to procreate.