sullenness vs sourness

sullenness and sourness both are nouns.

Word	Noun	Adjective	Verb	Adverb
sullenness	Yes	No	No	No
sourness	Yes	No	No	No

As nouns, sullenness and sourness are synonyms defined as:

Other synonyms of sullenness include moroseness, sulkiness.

sullenness (noun)	sourness (noun)
a sullen moody resentful disposition	the property of being acidic
a gloomy ill-tempered feeling	a sullen moody resentful disposition
	the taste experience when vinegar or lemon juice is taken into the mouth