assemblyman vs adult male

assemblyman and adult male both are nouns.

Word	Noun	Adjective	Verb	Adverb
assemblyman	Yes	No	No	No
adult male	Yes	No	No	No

As nouns, adult male is a hypernym of assemblyman; that is, adult male is a word with a broader meaning than assemblyman:

Other hypernyms of assemblyman include man, representative.

assemblyman (noun)	adult male (noun)
someone who is a member of a legislative assembly	an adult person who is male (as opposed to a woman)