altruist vs giver

altruist and giver both are nouns.

Word	Noun	Adjective	Verb	Adverb
altruist	Yes	No	No	No
giver	Yes	No	No	No

As nouns, giver is a hypernym of altruist; that is, giver is a word with a broader meaning than altruist:

altruist: someone who makes charitable donations intended to increase human well-being
giver: person who makes a gift of property

Other hypernyms of altruist include bestower, conferrer, donor, presenter.

altruist (noun)	giver (noun)
someone who makes charitable donations intended to increase human well-being	person who makes a gift of property
	someone who devotes himself completely