flare up vs ignite

flare up and ignite both are verbs.

Word	Noun	Adjective	Verb	Adverb
flare up	No	No	Yes	No
ignite	No	No	Yes	No

As verbs, ignite is a hypernym of flare up; that is, ignite is a word with a broader meaning than flare up:

Other hypernyms of flare up include light.

flare up (verb)	ignite (verb)
erupt or intensify suddenly	start or maintain a fire in
ignite quickly and suddenly, especially after having died down	arouse or excite feelings and passions
	cause to start burning; subject to fire or great heat
	start to burn or burst into flames