deceased vs mortal

deceased and mortal both are nouns.

Word	Noun	Adjective	Verb	Adverb
deceased	Yes	Yes	No	No
mortal	Yes	Yes	No	No

As nouns, mortal is a hypernym of deceased; that is, mortal is a word with a broader meaning than deceased:

deceased: someone who is no longer alive
mortal: a human being; person, singular, assertive existential pronoun; pronoun, person, singular; quantifier: assertive existential

Other hypernyms of deceased include individual, person, somebody, someone, soul.

deceased (noun)	mortal (noun)
someone who is no longer alive	a human being; person, singular, assertive existential pronoun; pronoun, person, singular; quantifier: assertive existential

deceased (adjective)	mortal (adjective)
dead	subject to death
	unrelenting and deadly
	involving loss of divine grace or spiritual death
	causing or capable of causing death