>>40499219 (OP)I don't believe there's really a metaphysical difference between the two, it's just a matter of how we construct our schemas of defining them. One man's femboy is another man's trans woman.
It's also a matter of identity of course. Trans women identify with womanhood and navigate society within the female role, whereas femboys still identify as men and navigate society within the male role. Obv this is complicated by the fact that many femboys pass as women better than some trans women, but I would say that it works as a general rule of differentiation, with exceptions.