spontaneousness vs naturalness

spontaneousness and naturalness both are nouns.

Word	Noun	Adjective	Verb	Adverb
spontaneousness	Yes	No	No	No
naturalness	Yes	No	No	No

As nouns, naturalness is a hypernym of spontaneousness; that is, naturalness is a word with a broader meaning than spontaneousness:

spontaneousness: the quality of being spontaneous and coming from natural feelings without constraint
naturalness: the quality of being natural or based on natural principles

spontaneousness (noun)	naturalness (noun)
the quality of being spontaneous and coming from natural feelings without constraint	the quality of being natural or based on natural principles
	the likeness of a representation to the thing represented
	the quality of innocent naivete