incendiary vs instigative

incendiary is a noun but instigative is not a noun.

Word	Noun	Adjective	Verb	Adverb
incendiary	Yes	Yes	No	No
instigative	No	Yes	No	No

As adjectives, incendiary and instigative are synonyms defined as:

Other synonyms of incendiary include incitive, inflammatory, rabble-rousing, seditious.

incendiary (noun)	instigative (noun)
a bomb that is designed to start fires; is most effective against flammable targets (such as fuel)
a criminal who illegally sets fire to property

incendiary (adjective)	instigative (adjective)
involving deliberate burning of property	arousing to action or rebellion
capable of catching fire spontaneously or causing fires or burning readily
arousing to action or rebellion