Uruguay River vs river

Uruguay River and river both are nouns.

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

Uruguay River (noun)	river (noun)
a South American river that arises in southern Brazil and flows south to the Rio de la Plata; the northern section forms the boundary between Argentina and Brazil and the southern section forms the boundary between Argentina and Uruguay	a large natural stream of water (larger than a creek)