self-importance vs swelled head

self-importance and swelled head both are nouns.

Word	Noun	Adjective	Verb	Adverb
self-importance	Yes	No	No	No
swelled head	Yes	No	No	No

As nouns, self-importance and swelled head are synonyms defined as:

self-importance and swelled head: an exaggerated opinion of your own importance

Other synonyms of self-importance include egotism.

self-importance (noun)	swelled head (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