resentment vs rancour

resentment and rancour both are nouns.

Word	Noun	Adjective	Verb	Adverb
resentment	Yes	No	No	No
rancour	Yes	No	No	No

As nouns, resentment and rancour are synonyms defined as:

Other synonyms of resentment include bitterness, gall, rancor.

resentment (noun)	rancour (noun)
a feeling of deep and bitter anger and ill-will	a feeling of deep and bitter anger and ill-will