simpleness vs easiness

simpleness and easiness both are nouns.

Word	Noun	Adjective	Verb	Adverb
simpleness	Yes	No	No	No
easiness	Yes	No	No	No

As nouns, simpleness and easiness are synonyms defined as:

Other synonyms of simpleness include ease, simplicity.

simpleness (noun)	easiness (noun)
the quality of being simple or uncompounded	the quality of being easy in behavior or style
lack of ornamentation	freedom from difficulty or hardship or effort
freedom from difficulty or hardship or effort	a feeling of refreshing tranquility and an absence of tension or worry
a lack of penetration or subtlety