swelled head vs egotism

swelled head and egotism both are nouns.

Word	Noun	Adjective	Verb	Adverb
swelled head	Yes	No	No	No
egotism	Yes	No	No	No

As nouns, swelled head and egotism are synonyms defined as:

Other synonyms of swelled head include self-importance.

swelled head (noun)	egotism (noun)
an exaggerated opinion of your own importance	an exaggerated opinion of your own importance
	an inflated feeling of pride in your superiority to others