restfulness vs inactivity

restfulness and inactivity both are nouns.

Word	Noun	Adjective	Verb	Adverb
restfulness	Yes	No	No	No
inactivity	Yes	No	No	No

As nouns, inactivity is a hypernym of restfulness; that is, inactivity is a word with a broader meaning than restfulness:

Other hypernyms of restfulness include inactiveness, inertia.

restfulness (noun)	inactivity (noun)
the attribute of being restful	being inactive; being less active
	a disposition to remain inactive or inert
	the state of being inactive