stratum vs subpopulation

stratum and subpopulation both are nouns.

Word	Noun	Adjective	Verb	Adverb
stratum	Yes	No	No	No
subpopulation	Yes	No	No	No

As nouns, subpopulation is a hypernym of stratum; that is, subpopulation is a word with a broader meaning than stratum:

stratum (noun)	subpopulation (noun)
an abstract place usually conceived as having depth	a population that is part of a larger population
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)