boy vs adult male

boy and adult male both are nouns.

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

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

Other hypernyms of boy include man.

boy (noun)	adult male (noun)
a youthful male person	an adult person who is male (as opposed to a woman)
(ethnic slur) offensive and disparaging term for Black man
a friendly informal reference to a grown man
a male human offspring