rancor vs grievance

rancor and grievance both are nouns.

Word	Noun	Adjective	Verb	Adverb
rancor	Yes	No	No	No
grievance	Yes	No	No	No

As nouns, grievance is a hyponym of rancor; that is, grievance is a word with a more specific, narrower meaning than rancor:

Other hyponyms of rancor include heartburning, huffishness, sulkiness, grudge, score, enviousness, envy.

rancor (noun)	grievance (noun)
a feeling of deep and bitter anger and ill-will	a complaint about a (real or imaginary) wrong that causes resentment and is grounds for action
	an allegation that something imposes an illegal obligation or denies some legal right or causes injustice
	a resentment strong enough to justify retaliation