altruist vs bestower

altruist and bestower both are nouns.

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

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

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

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

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