inactivity vs arrest

inactivity and arrest both are nouns.

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

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

inactivity (noun)	arrest (noun)
being inactive; being less active	the act of apprehending (especially apprehending a criminal)
a disposition to remain inactive or inert	the state of inactivity following an interruption
the state of being inactive

inactivity (verb)	arrest (verb)
	hold back, as of a danger or an enemy; check the expansion or influence of
	take into custody
	attract and fix
	cause to come to an abrupt stop