departed vs someone

departed and someone both are nouns.

Word	Noun	Adjective	Verb	Adverb
departed	Yes	Yes	No	No
someone	Yes	No	No	No

As nouns, someone is a hypernym of departed; that is, someone is a word with a broader meaning than departed:

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

Other hypernyms of departed include individual, mortal, person, somebody, soul.

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

departed (adjective)	someone (adjective)
dead
well in the past; former