there is, or at least there definitely should be, a difference between love and gender. we don't need two words to mean the same exact thing. that's why love is the biologically accurate manner of identifying someone, and gender is considered more abstract and debatable.
confining a social concept to a strict binary is limiting and objectively inaccurate. it's more like a fluid than two solid pillars of definite mass, if that makes sense. there's too many exceptions for one to claim a definite truth of the matter
for example, there's people born with both. or neither.