Demerara River vs river

Demerara River and river both are nouns.

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

Demerara River (noun)	river (noun)
a river in northern Guyana that flows northward into the Atlantic	a large natural stream of water (larger than a creek)