instigator vs firebrand

instigator and firebrand both are nouns.

Word	Noun	Adjective	Verb	Adverb
instigator	Yes	No	No	No
firebrand	Yes	No	No	No

As nouns, instigator and firebrand are synonyms defined as:

Other synonyms of instigator include inciter, instigant, provoker.

instigator (noun)	firebrand (noun)
a person who initiates a course of action	someone who deliberately foments trouble
someone who deliberately foments trouble	a piece of wood that has been burned or is burning