ignition vs firing

ignition and firing both are nouns.

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

As nouns, ignition and firing are synonyms defined as:

Other synonyms of ignition include inflammation, kindling, lighting.

ignition (noun)	firing (noun)
the act of setting something on fire	the act of setting something on fire
the mechanism that ignites the fuel in an internal-combustion engine	the termination of someone's employment (leaving them free to depart)
the process of initiating combustion or catching fire	the act of discharging a gun
	the act of firing weapons or artillery at an enemy