river vs Neosho River

river and Neosho River both are nouns.

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

river (noun)	Neosho River (noun)
a large natural stream of water (larger than a creek)	a river that rises in eastern Kansas and flows eastward into Oklahoma to become a tributary of the Arkansas River