iron man vs adult male

iron man and adult male both are nouns.

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

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

Other hypernyms of iron man include man.

iron man (noun)	adult male (noun)
a strong man of exceptional physical endurance	an adult person who is male (as opposed to a woman)