opera hat vs dress hat

opera hat and dress hat both are nouns.

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

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

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

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

opera hat (noun)	dress hat (noun)
a man's hat with a tall crown; usually covered with silk or with beaver fur	a man's hat with a tall crown; usually covered with silk or with beaver fur