working-class vs blue-collar

working-class and blue-collar both are adjectives.

Word	Noun	Adjective	Verb	Adverb
working-class	No	Yes	No	No
blue-collar	No	Yes	No	No

As adjectives, working-class and blue-collar are synonyms defined as:

working-class and blue-collar: of those who work for wages especially manual or industrial laborers

Other synonyms of working-class include propertyless, wage-earning.

working-class (adjective)	blue-collar (adjective)
working for hourly wages rather than fixed (e.g. annual) salaries	of or designating manual industrial work or workers
of those who work for wages especially manual or industrial laborers	of those who work for wages especially manual or industrial laborers