past vs departed

past and departed both are nouns.

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

past (noun)	departed (noun)
a verb tense that expresses actions or states in the past	someone who is no longer alive
the time that has elapsed
a earlier period in someone's life (especially one that they have reason to keep secret)

past (adjective)	departed (adjective)
earlier than the present time; no longer current	dead
of a person who has held and relinquished a position or office	well in the past; former

past (adverb)	departed (adverb)
so as to pass a given point