I think it’s helpful is to break down “gender” into some more specific components, since even us folks within the transgender spectrum often use “gender” to describe a collection of related, but really separate, things. Which is why we’re often uncertain where we may fall on the spectrum.
First off, there’s the difference between “sex” and “gender”—the former is what’s between your legs and the latter is what’s between your ears. The feeling of being alienated from one’s body to me is one of the big dividing lines on the spectrum. I might want to wear breastforms and tuck while I’m crossdressed, but I’ve got no desire to have actual breasts or to trade my genitals.
Within “gender” there’s two aspects. The first is the “gender role” aspects that are external to oneself. Historically, FTM crossdressing was engaged by many women who wouldn’t be considered transsexuals because passing as men allowed them freedoms and opportunities that they weren’t allowed as women. Conversely, I think the chance to take a “gender role vacation” is a major motivator for many crossdressers—to do things like be “pretty,” to be “passive” and all the other things that they envy in their idea about what a women’s life is life. It is for me.
The second aspect I’ve yet to come up with a good name for, but it’s the internally-focused aspects of gender, i.e. do you see your personality as being “masculine” or “feminine.” Obviously this has a blurry boundary with “gender role” (since society dictates what’s “masculine” and what’s “feminine”) but again among crossdressers, I often see a rationale expressed that doing so is a chance for them to express a part of themselves that they don’t feel allowed to do so as “men.” Again, that’s one reason for my own crossdressing.
Breaking these things out, to me helps better explain why we see such as a spectrum. At one end are TSs, who often feel dyphoric on all three aspects. At the other, you’ve got people who just are interested in the external trappings, typically the clothes. And transgenderists (i.e. those who choose to live as the opposite sex but who aren’t interested in genital reassignment surgery, although they might do electrolysis, hormones and/or some surgery) in my experience often seem to feel dysphoric in regards to gender roles and gender self-identity, but not in terms of their bodies.
Finally, there’s the issue of sexual orientation (i.e. who you’re attacted to), which is independent of these other three aspects.
And there’s all sorts of other variations among all of these, which is why there’s so much variety to folks on the transgender spectrum.
