unmarried man vs adult male

unmarried man and adult male both are nouns.

Word	Noun	Adjective	Verb	Adverb
unmarried man	Yes	No	No	No
adult male	Yes	No	No	No

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

Other hypernyms of unmarried man include man.

unmarried man (noun)	adult male (noun)
a man who has never been married	an adult person who is male (as opposed to a woman)