self-abnegation vs selflessness

self-abnegation and selflessness both are nouns.

Word	Noun	Adjective	Verb	Adverb
self-abnegation	Yes	No	No	No
selflessness	Yes	No	No	No

As nouns, selflessness is a hypernym of self-abnegation; that is, selflessness is a word with a broader meaning than self-abnegation:

self-abnegation: renunciation of your own interests in favor of the interests of others
selflessness: acting with less concern for yourself than for the success of the joint activity

Other hypernyms of self-abnegation include forgoing, forswearing, renunciation, self-sacrifice.

self-abnegation (noun)	selflessness (noun)
renunciation of your own interests in favor of the interests of others	acting with less concern for yourself than for the success of the joint activity
	the quality of unselfish concern for the welfare of others