bloodletting vs massacre

bloodletting and massacre both are nouns.

Word	Noun	Adjective	Verb	Adverb
bloodletting	Yes	No	No	No
massacre	Yes	No	Yes	No

As nouns, massacre is a hypernym of bloodletting; that is, massacre is a word with a broader meaning than bloodletting:

Other hypernyms of bloodletting include butchery, carnage, mass murder, slaughter.

bloodletting (noun)	massacre (noun)
formerly used as a treatment to reduce excess blood (one of the four humors of medieval medicine)	the savage and excessive killing of many people
indiscriminate slaughter

bloodletting (verb)	massacre (verb)
	kill a large number of people indiscriminately