firing vs inactivation

firing and inactivation both are nouns.

Word	Noun	Adjective	Verb	Adverb
firing	Yes	No	No	No
inactivation	Yes	No	No	No

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

firing: the termination of someone's employment (leaving them free to depart)
inactivation: breaking up a military unit (by transfers or discharges)

firing (noun)	inactivation (noun)
the act of setting something on fire	breaking up a military unit (by transfers or discharges)
the termination of someone's employment (leaving them free to depart)	the process of rendering inactive
the act of discharging a gun
the act of firing weapons or artillery at an enemy