collateral damage vs casualty

collateral damage and casualty both are nouns.

Word	Noun	Adjective	Verb	Adverb
collateral damage	Yes	No	No	No
casualty	Yes	No	No	No

As nouns, casualty is a hypernym of collateral damage; that is, casualty is a word with a broader meaning than collateral damage:

collateral damage: (euphemism) inadvertent casualties and destruction inflicted on civilians in the course of military operations
casualty: an accident that causes someone to die

Other hypernyms of collateral damage include fatal accident.

collateral damage (noun)	casualty (noun)
(euphemism) inadvertent casualties and destruction inflicted on civilians in the course of military operations	a decrease of military personnel or equipment
	an accident that causes someone to die
	someone injured or killed in an accident
	someone injured or killed or captured or missing in a military engagement