egotism vs ego

egotism and ego both are nouns.

Word	Noun	Adjective	Verb	Adverb
egotism	Yes	No	No	No
ego	Yes	No	No	No

As nouns, egotism and ego are synonyms defined as:

egotism and ego: an inflated feeling of pride in your superiority to others

Other synonyms of egotism include self-importance.

egotism (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