old school vs class

old school and class both are nouns.

Word	Noun	Adjective	Verb	Adverb
old school	Yes	No	No	No
class	Yes	No	Yes	No

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

Other hypernyms of old school include social class, socio-economic class, stratum.

old school (noun)	class (noun)
a class of people favoring traditional ideas	education imparted in a series of lessons or meetings
	elegance in dress or behavior
	a collection of things sharing a common attribute
	people having the same social, economic, or educational status
	(biology) a taxonomic group containing one or more orders
	a body of students who are taught together
	a body of students who graduate together
	a league ranked by quality

old school (verb)	class (verb)
	arrange or order by classes or categories