self-sacrifice vs selflessness

self-sacrifice and selflessness both are nouns.

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

As nouns, self-sacrifice and selflessness are synonyms defined as:

self-sacrifice and selflessness: acting with less concern for yourself than for the success of the joint activity

self-sacrifice (noun)	selflessness (noun)
acting with less concern for yourself than for the success of the joint activity	acting with less concern for yourself than for the success of the joint activity
	the quality of unselfish concern for the welfare of others