fool's cap vs chapeau

fool's cap and chapeau both are nouns.

Word	Noun	Adjective	Verb	Adverb
fool's cap	Yes	No	No	No
chapeau	Yes	No	No	No

As nouns, chapeau is a hypernym of fool's cap; that is, chapeau is a word with a broader meaning than fool's cap:

fool's cap: a cone-shaped paper hat formerly placed on the head of slow or lazy pupils
chapeau: headdress that protects the head from bad weather; has shaped crown and usually a brim

Other hypernyms of fool's cap include hat, lid.

fool's cap (noun)	chapeau (noun)
a cone-shaped paper hat formerly placed on the head of slow or lazy pupils	headdress that protects the head from bad weather; has shaped crown and usually a brim