upper class vs social class

upper class and social class both are nouns.

Word	Noun	Adjective	Verb	Adverb
upper class	Yes	No	No	No
social class	Yes	No	No	No

As nouns, social class is a hypernym of upper class; that is, social class is a word with a broader meaning than upper class:

upper class: the class occupying the highest position in the social hierarchy
social class: people having the same social, economic, or educational status

Other hypernyms of upper class include class, socio-economic class, stratum.

upper class (noun)	social class (noun)
the class occupying the highest position in the social hierarchy	people having the same social, economic, or educational status