working-class vs low-class

working-class and low-class both are adjectives.

Word	Noun	Adjective	Verb	Adverb
working-class	No	Yes	No	No
low-class	No	Yes	No	No

working-class (adjective)	low-class (adjective)
working for hourly wages rather than fixed (e.g. annual) salaries	occupying the lowest socioeconomic position in a society
of those who work for wages especially manual or industrial laborers