river vs Yazoo River

river and Yazoo River both are nouns.

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

river (noun)	Yazoo River (noun)
a large natural stream of water (larger than a creek)	a river that rises in west central Mississippi and flows southwest to empty into the Mississippi River above Vicksburg