fashion plate vs adult male

fashion plate and adult male both are nouns.

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

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

Other hypernyms of fashion plate include man.

fashion plate (noun)	adult male (noun)
a plate illustrating the latest fashion in dress	an adult person who is male (as opposed to a woman)
a man who is much concerned with his dress and appearance