sulkiness vs rancour

sulkiness and rancour both are nouns.

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

As nouns, rancour is a hypernym of sulkiness; that is, rancour is a word with a broader meaning than sulkiness:

Other hypernyms of sulkiness include bitterness, gall, rancor, resentment.

sulkiness (noun)	rancour (noun)
a sullen moody resentful disposition	a feeling of deep and bitter anger and ill-will
a feeling of sulky resentment
a mood or display of sullen aloofness or withdrawal