know-it-all vs swellhead

know-it-all and swellhead both are nouns.

Word	Noun	Adjective	Verb	Adverb
know-it-all	Yes	No	No	No
swellhead	Yes	No	No	No

As nouns, swellhead is a hypernym of know-it-all; that is, swellhead is a word with a broader meaning than know-it-all:

know-it-all: someone who thinks he knows everything and refuses to accept advice or information from others
swellhead: a conceited and self-centered person

Other hypernyms of know-it-all include egoist, egotist.

know-it-all (noun)	swellhead (noun)
someone who thinks he knows everything and refuses to accept advice or information from others	a conceited and self-centered person