top hat vs chapeau

top hat and chapeau both are nouns.

Word	Noun	Adjective	Verb	Adverb
top hat	Yes	No	No	No
chapeau	Yes	No	No	No

As nouns, chapeau is a hypernym of top hat; that is, chapeau is a word with a broader meaning than top hat:

top hat: a man's hat with a tall crown; usually covered with silk or with beaver fur
chapeau: headdress that protects the head from bad weather; has shaped crown and usually a brim

Other hypernyms of top hat include hat, lid, man's clothing.

top hat (noun)	chapeau (noun)
a man's hat with a tall crown; usually covered with silk or with beaver fur	headdress that protects the head from bad weather; has shaped crown and usually a brim