river vs Moreau River

river and Moreau River both are nouns.

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

river (noun)	Moreau River (noun)
a large natural stream of water (larger than a creek)	a river that rises in western South Dakota and flows eastward to the Missouri River