stratum vs class structure

stratum and class structure both are nouns.

Word	Noun	Adjective	Verb	Adverb
stratum	Yes	No	No	No
class structure	Yes	No	No	No

stratum (noun)	class structure (noun)
an abstract place usually conceived as having depth	the organization of classes within a society
a subpopulation divided into a stratified sampling
people having the same social, economic, or educational status
one of several parallel layers of material arranged one on top of another (such as a layer of tissue or cells in an organism or a layer of sedimentary rock)