existential vs existence

existential is not a noun while existence is a noun.

Word	Noun	Adjective	Verb	Adverb
existential	No	Yes	No	No
existence	Yes	No	No	No

existential (noun)	existence (noun)
	everything that exists anywhere
	the state or fact of existing

existential (adjective)	existence (adjective)
relating to or dealing with existence (especially with human existence)
of or as conceived by existentialism
derived from experience or the experience of existence