antique vs old-hat

antique is a noun but old-hat is not a noun.

Word	Noun	Adjective	Verb	Adverb
antique	Yes	Yes	Yes	No
old-hat	No	Yes	No	No

As adjectives, antique and old-hat are synonyms defined as:

Other synonyms of antique include demode, ex, old-fashioned, outmoded, passe, passee.

antique (noun)	old-hat (noun)
any piece of furniture or decorative object or the like produced in a former period and valuable because of its beauty or rarity
an elderly man

antique (adjective)	old-hat (adjective)
made in or typical of earlier times and valued for its age	out of fashion
out of fashion	repeated too often; overfamiliar through overuse
belonging to or lasting from times long ago

antique (verb)	old-hat (verb)
give an antique appearance to
shop for antiques