I live in the United States, I'm not gay, and I understand them. They go back at least to the 1970s. I would expect an ordinary English dictionary to include them, let's check.
Femme, n. 1. Slang: A person, especially a lesbian or a gay man, who exhibits stereotypical feminine traits, often in an exaggerated way."
Butch, adj. Slang: Exhibiting stereotypically masculine appearance or behavior. Used especially of lesbians and gay men. n. 1. Slang: one who is butch.
Incidentally, like you, I thought they applied only to lesbians, but the dictionary says they are also used for gay men. That's news to me.