Volga River vs river

Volga River and river both are nouns.

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

Volga River (noun)	river (noun)
a Russian river; the longest river in Europe; flows into the Caspian Sea	a large natural stream of water (larger than a creek)