adult male vs adult

adult male and adult both are nouns.

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

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

Other hypernyms of adult male include grownup, male, male person.

adult male (noun)	adult (noun)
an adult person who is male (as opposed to a woman)	any mature animal
	a fully developed person from maturity onward

adult male (adjective)	adult (adjective)
	(of animals) fully developed
	designed to arouse lust