common sense vs discernment

common sense and discernment both are nouns.

Word	Noun	Adjective	Verb	Adverb
common sense	Yes	No	No	No
discernment	Yes	No	No	No

As nouns, discernment is a hypernym of common sense; that is, discernment is a word with a broader meaning than common sense:

common sense: sound practical judgment
discernment: the mental ability to understand and discriminate between relations

Other hypernyms of common sense include judgement, judgment, sagaciousness, sagacity.

common sense (noun)	discernment (noun)
sound practical judgment	the trait of judging wisely and objectively
	the mental ability to understand and discriminate between relations
	the cognitive condition of someone who understands
	perception of that which is obscure
	delicate discrimination (especially of esthetic values)