YSK: Trans is an adjective. So "trans man" or "trans woman" describes someone who is a man or woman (respectively) by virtue of being trans. You can think of it as having transitioned *to* man or woman.
from /r/YouShouldKnow
YSK：变性是一个形容词。因此，"变性男人 "或 "变性女人 "描述的是因变性而成为男人或女人（分别）的人。你可以把它看作是已经过渡到**男人或女人。