altruism vs unselfishness

altruism and unselfishness both are nouns.

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

As nouns, unselfishness is a hypernym of altruism; that is, unselfishness is a word with a broader meaning than altruism:

altruism: the quality of unselfish concern for the welfare of others
unselfishness: the quality of not putting yourself first but being willing to give your time or money or effort etc. for others

altruism (noun)	unselfishness (noun)
the quality of unselfish concern for the welfare of others	acting generously
	the quality of not putting yourself first but being willing to give your time or money or effort etc. for others