river vs Cumberland River

river and Cumberland River both are nouns.

Word	Noun	Adjective	Verb	Adverb
river	Yes	No	No	No
Cumberland River	Yes	No	No	No

river (noun)	Cumberland River (noun)
a large natural stream of water (larger than a creek)	a river that rises in southeastern Kentucky and flows westward through northern Tennessee to become a tributary of the Ohio River in southwestern Kentucky