popinjay vs swellhead

popinjay and swellhead both are nouns.

Word	Noun	Adjective	Verb	Adverb
popinjay	Yes	No	No	No
swellhead	Yes	No	No	No

As nouns, swellhead is a hypernym of popinjay; that is, swellhead is a word with a broader meaning than popinjay:

Other hypernyms of popinjay include egoist, egotist.

popinjay (noun)	swellhead (noun)
an archaic term for a parrot	a conceited and self-centered person
a vain and talkative person (chatters like a parrot)