fatality vs casualty

fatality and casualty both are nouns.

Word	Noun	Adjective	Verb	Adverb
fatality	Yes	No	No	No
casualty	Yes	No	No	No

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

Other hyponyms of fatality include killing, violent death, fatal accident.

fatality (noun)	casualty (noun)
the quality of being able to cause death or fatal disasters	a decrease of military personnel or equipment
a death resulting from an accident or a disaster	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