unobserved fire vs firing

unobserved fire and firing both are nouns.

Word	Noun	Adjective	Verb	Adverb
unobserved fire	Yes	No	No	No
firing	Yes	No	No	No

As nouns, firing is a hypernym of unobserved fire; that is, firing is a word with a broader meaning than unobserved fire:

unobserved fire: fire for which the point of impact (the bursts) cannot be observed
firing: the act of firing weapons or artillery at an enemy

Other hypernyms of unobserved fire include fire.

unobserved fire (noun)	firing (noun)
fire for which the point of impact (the bursts) cannot be observed	the act of setting something on fire
	the termination of someone's employment (leaving them free to depart)
	the act of discharging a gun
	the act of firing weapons or artillery at an enemy