masses vs the great unwashed

masses and the great unwashed both are nouns.

Word	Noun	Adjective	Verb	Adverb
masses	Yes	No	No	No
the great unwashed	Yes	No	No	No

As nouns, masses and the great unwashed are synonyms defined as:

Other synonyms of masses include hoi polloi, mass, multitude, people.

masses (noun)	the great unwashed (noun)
the common people generally	the common people generally