millinery vs chapeau

millinery and chapeau both are nouns.

Word	Noun	Adjective	Verb	Adverb
millinery	Yes	No	No	No
chapeau	Yes	No	No	No

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

millinery: hats for women; the wares sold by a milliner
chapeau: headdress that protects the head from bad weather; has shaped crown and usually a brim

Other hypernyms of millinery include hat, lid.

millinery (noun)	chapeau (noun)
hats for women; the wares sold by a milliner	headdress that protects the head from bad weather; has shaped crown and usually a brim
shop selling women's hats