apolian

Crossdresser/Transvestite: To dress in the attire of the opposite gender for sexual arousal (usually). A sexual kink, so to speak.
Trangendered: One that feels they were born the wrong gender (or otherwise wishes to change gender).
Transexual: One that feels they were born the wrong gender (or otherwise wishes to change gender) AND is currently in the transition of correcting that. Where transition begins I guess could be simply at the point of initial consultation with psychological & medical professionals.

I think society has made it hard or less likely for females to feel such a thing. A simple example of "why" is how females can select a career of whatever they choose without ridicule eg. sales assitant in a menswear store, whereas if a males was a sales assistant in a womens store he would accused of being gay.
I only point that out because I think to all females asking "how do you know" - it's probably harder for you to imagine such a thing because you live in a world where you're (females) not shunned for (hardly) any expression of masculinity eg. you can take up kickboxing without being accused of being a lesbian & you won't become less attractive in the eyes of most males. A male that takes up ballet, wears a g-string, becomes a receptionist, etc. doesn't tend to receive the same neutral treatment.

I should get to the point and answer your question: imagine tomorrow you wake up and discover you now have the body of a muscular male. Would this make you desire to kiss a female & lose interest in men? Would it make you want to walk down the street in a pair of baggy jeans & hate the thought of wearing a dress? More importantly, would you close your eyes & think to yourself "I am a man"?
Females: everything you mentally desire/feel/know about yourself is what an MTF transexual would desire/feel/know about themself, except they're wrapped in the wrong shell.

*Note: any MTF may solely be interested in sex with females only. Sexual desire is just one element & does not determine sexual identity but whatever any particular transexual's sexuality may be, they would still be well aware of what their sexual identity is.