self-importance vs ego

self-importance and ego both are nouns.

Word	Noun	Adjective	Verb	Adverb
self-importance	Yes	No	No	No
ego	Yes	No	No	No

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

self-importance and ego: an inflated feeling of pride in your superiority to others

Other synonyms of self-importance include egotism.

self-importance (noun)	ego (noun)
an exaggerated opinion of your own importance	(psychoanalysis) the conscious mind
an inflated feeling of pride in your superiority to others	your consciousness of your own identity
	an inflated feeling of pride in your superiority to others