river vs Flint River

river and Flint River both are nouns.

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

river (noun)	Flint River (noun)
a large natural stream of water (larger than a creek)	a river in western Georgia that flows generally south to join the Chattahoochee River at the Florida border where they form the Apalachicola River