old man vs golden ager

old man and golden ager both are nouns.

Word	Noun	Adjective	Verb	Adverb
old man	Yes	No	No	No
golden ager	Yes	No	No	No

As nouns, golden ager is a hypernym of old man; that is, golden ager is a word with a broader meaning than old man:

Other hypernyms of old man include adult male, man, old person, oldster, senior citizen.

old man (noun)	golden ager (noun)
an informal term for your father	an elderly person
a man who is very old
a familiar term of address for a man
(slang) boss
aromatic herb of temperate Eurasia and North Africa having a bitter taste used in making the liqueur absinthe