easiness vs tranquillity

easiness and tranquillity both are nouns.

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

As nouns, tranquillity is a hypernym of easiness; that is, tranquillity is a word with a broader meaning than easiness:

easiness: a feeling of refreshing tranquility and an absence of tension or worry
tranquillity: a state of peace and quiet

Other hypernyms of easiness include quietness, quietude, tranquility.

easiness (noun)	tranquillity (noun)
the quality of being easy in behavior or style	a disposition free from stress or emotion
freedom from difficulty or hardship or effort	a state of peace and quiet
a feeling of refreshing tranquility and an absence of tension or worry	an untroubled state; free from disturbances