working class vs proletariat

working class and proletariat both are nouns.

Word	Noun	Adjective	Verb	Adverb
working class	Yes	No	No	No
proletariat	Yes	No	No	No

As nouns, working class and proletariat are synonyms defined as:

working class and proletariat: a social class comprising those who do manual labor or work for wages

Other synonyms of working class include labor, labour.

working class (noun)	proletariat (noun)
a social class comprising those who do manual labor or work for wages	a social class comprising those who do manual labor or work for wages