covering fire vs firing

covering fire and firing both are nouns.

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

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

covering fire: fire that makes it difficult for the enemy to fire on your own individuals or formations
firing: the act of firing weapons or artillery at an enemy

Other hypernyms of covering fire include fire.

covering fire (noun)	firing (noun)
fire that makes it difficult for the enemy to fire on your own individuals or formations	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