altruism vs selflessness

altruism and selflessness both are nouns.

Word	Noun	Adjective	Verb	Adverb
altruism	Yes	No	No	No
selflessness	Yes	No	No	No

As nouns, altruism and selflessness are synonyms defined as:

altruism and selflessness: the quality of unselfish concern for the welfare of others

altruism (noun)	selflessness (noun)
the quality of unselfish concern for the welfare 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