fraternity vs stratum

fraternity and stratum both are nouns.

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

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

Other hypernyms of fraternity include class, social class, socio-economic class.

fraternity (noun)	stratum (noun)
people engaged in a particular occupation	an abstract place usually conceived as having depth
a social club for male undergraduates	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)