Methuselah vs adult male

Methuselah and adult male both are nouns.

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

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

Other hypernyms of Methuselah include man, golden ager, old person, oldster, senior citizen.

Methuselah (noun)	adult male (noun)
(Old Testament) a patriarch (grandfather of Noah) who is said to have lived 969 years	an adult person who is male (as opposed to a woman)
a man who is very old