common people vs folk

common people and folk both are nouns.

Word	Noun	Adjective	Verb	Adverb
common people	Yes	No	No	No
folk	Yes	No	No	No

As nouns, common people and folk are synonyms defined as:

Other synonyms of common people include folks.

common people (noun)	folk (noun)
people in general (often used in the plural)	the traditional and typically anonymous music that is an expression of the life of people in a community
	people in general (often used in the plural)
	a social division of (usually preliterate) people
	people descended from a common ancestor