river vs Dnieper River

river and Dnieper River both are nouns.

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

river (noun)	Dnieper River (noun)
a large natural stream of water (larger than a creek)	a river that rises in Russia near Smolensk and flowing south through Belarus and Ukraine to empty into the Black Sea