spontaneousness vs spontaneity

spontaneousness and spontaneity both are nouns.

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

As nouns, spontaneousness and spontaneity are synonyms defined as:

spontaneousness and spontaneity: the quality of being spontaneous and coming from natural feelings without constraint

spontaneousness (noun)	spontaneity (noun)
the quality of being spontaneous and coming from natural feelings without constraint	the quality of being spontaneous and coming from natural feelings without constraint