non-U vs low-class

non-U and low-class both are adjectives.

Word	Noun	Adjective	Verb	Adverb
non-U	No	Yes	No	No
low-class	No	Yes	No	No

non-U (adjective)	low-class (adjective)
not characteristic of the upper classes especially in language use	occupying the lowest socioeconomic position in a society