instigate vs stir up

instigate and stir up both are verbs.

Word	Noun	Adjective	Verb	Adverb
instigate	No	No	Yes	No
stir up	No	No	Yes	No

As verbs, instigate and stir up are synonyms defined as:

Other synonyms of instigate include incite, set off.

instigate (verb)	stir up (verb)
provoke or stir up	provoke or stir up
serve as the inciting cause of	change the arrangement or position of
	arouse or excite feelings and passions
	try to stir up public opinion