vestryman vs adult male

vestryman and adult male both are nouns.

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

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

Other hypernyms of vestryman include church officer, man.

vestryman (noun)	adult male (noun)
a man who is a member of a church vestry	an adult person who is male (as opposed to a woman)