cause vs instigate

cause is a noun but instigate is not a noun.

Word	Noun	Adjective	Verb	Adverb
cause	Yes	No	Yes	No
instigate	No	No	Yes	No

As verbs, instigate is a hyponym of cause; that is, instigate is a word with a more specific, narrower meaning than cause:

Other hyponyms of cause include decide, persuade, bring, solicit, encourage, let, lead, inspire, prompt, suborn, compel, obligate, oblige.

cause (noun)	instigate (noun)
any entity that produces an effect or is responsible for events or results
a comprehensive term for any proceeding in a court of law whereby an individual seeks a legal remedy
a series of actions advancing a principle or tending toward a particular end
a justification for something existing or happening
events that provide the generative force that is the origin of something

cause (verb)	instigate (verb)
cause to do; cause to act in a specified manner	provoke or stir up
give rise to; cause to happen or occur, not always intentionally	serve as the inciting cause of