donor vs altruist

donor and altruist both are nouns.

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

As nouns, altruist is a hyponym of donor; that is, altruist is a word with a more specific, narrower meaning than donor:

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

donor (noun)	altruist (noun)
person who makes a gift of property	someone who makes charitable donations intended to increase human well-being
(medicine) someone who gives blood or tissue or an organ to be used in another person (the host)