opera hat vs high hat

opera hat and high hat both are nouns.

Word	Noun	Adjective	Verb	Adverb
opera hat	Yes	No	No	No
high hat	Yes	No	No	No

As nouns, opera hat and high hat are synonyms defined as:

opera hat and high hat: a man's hat with a tall crown; usually covered with silk or with beaver fur

Other synonyms of opera hat include beaver, dress hat, silk hat, stovepipe, top hat, topper.

opera hat (noun)	high hat (noun)
a man's hat with a tall crown; usually covered with silk or with beaver fur	cymbals that are operated by a foot pedal
	a man's hat with a tall crown; usually covered with silk or with beaver fur