blood donor vs donor

blood donor and donor both are nouns.

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

As nouns, donor is a hypernym of blood donor; that is, donor is a word with a broader meaning than blood donor:

blood donor: someone who gives blood to be used for transfusions
donor: (medicine) someone who gives blood or tissue or an organ to be used in another person (the host)

blood donor (noun)	donor (noun)
someone who gives blood to be used for transfusions	person who makes a gift of property
	(medicine) someone who gives blood or tissue or an organ to be used in another person (the host)