North Platte River vs river

North Platte River and river both are nouns.

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

North Platte River (noun)	river (noun)
a river that rises in northern Colorado and flows northward into Wyoming and then eastward and southeastward through Nebraska where it joins the South Platte to form the Platte River	a large natural stream of water (larger than a creek)