blue-collar vs low-class

blue-collar and low-class both are adjectives.

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

blue-collar (adjective)	low-class (adjective)
of or designating manual industrial work or workers	occupying the lowest socioeconomic position in a society
of those who work for wages especially manual or industrial laborers