decedent vs dead person

decedent and dead person both are nouns.

Word	Noun	Adjective	Verb	Adverb
decedent	Yes	No	No	No
dead person	Yes	No	No	No

As nouns, decedent and dead person are synonyms defined as:

Other synonyms of decedent include dead soul, deceased, deceased person, departed.

decedent (noun)	dead person (noun)
someone who is no longer alive	someone who is no longer alive