Irishman vs adult male

Irishman and adult male both are nouns.

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

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

Other hypernyms of Irishman include Irelander, Irish person, man.

Irishman (noun)	adult male (noun)
a man who is a native or inhabitant of Ireland	an adult person who is male (as opposed to a woman)