blue-collar vs working-class

blue-collar and working-class both are adjectives.

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

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

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

Other synonyms of blue-collar include propertyless, wage-earning.

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