Platte River vs river

Platte River and river both are nouns.

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

Platte River (noun)	river (noun)
a river in Nebraska that flows eastward to become a tributary of the Missouri River	a large natural stream of water (larger than a creek)