equanimity vs serenity

equanimity and serenity both are nouns.

Word	Noun	Adjective	Verb	Adverb
equanimity	Yes	No	No	No
serenity	Yes	No	No	No

As nouns, serenity is a hyponym of equanimity; that is, serenity is a word with a more specific, narrower meaning than equanimity:

Other hyponyms of equanimity include aplomb, assuredness, cool, poise, sang-froid, placidity, quiet, repose, tranquility, tranquillity.

equanimity (noun)	serenity (noun)
steadiness of mind under stress	a disposition free from stress or emotion
	the absence of mental stress or anxiety