old-hat vs old-fashioned

old-hat and old-fashioned both are adjectives.

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

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

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

old-hat (adjective)	old-fashioned (adjective)
out of fashion	out of fashion
repeated too often; overfamiliar through overuse