unreality vs nonexistence

unreality and nonexistence both are nouns.

Word	Noun	Adjective	Verb	Adverb
unreality	Yes	No	No	No
nonexistence	Yes	No	No	No

As nouns, nonexistence is a hypernym of unreality; that is, nonexistence is a word with a broader meaning than unreality:

unreality: the state of being insubstantial or imaginary; not existing objectively or in fact
nonexistence: the state of not existing

Other hypernyms of unreality include nonentity.

unreality (noun)	nonexistence (noun)
the quality possessed by something that is unreal	the state of not existing
ineptitude in dealing with reality.
the state of being insubstantial or imaginary; not existing objectively or in fact