bowler hat vs chapeau

bowler hat and chapeau both are nouns.

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

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

bowler hat: a felt hat that is round and hard with a narrow brim
chapeau: headdress that protects the head from bad weather; has shaped crown and usually a brim

Other hypernyms of bowler hat include hat, lid.

bowler hat (noun)	chapeau (noun)
a felt hat that is round and hard with a narrow brim	headdress that protects the head from bad weather; has shaped crown and usually a brim