inactivity vs idling

inactivity and idling both are nouns.

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

As nouns, idling is a hyponym of inactivity; that is, idling is a word with a more specific, narrower meaning than inactivity:

Other hyponyms of inactivity include pause, wait, waiting, ease, relaxation, repose, rest, idleness, loafing, delay, holdup.

inactivity (noun)	idling (noun)
being inactive; being less active	having no employment
a disposition to remain inactive or inert
the state of being inactive