Nan River vs river

Nan River and river both are nouns.

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

Nan River (noun)	river (noun)
a river of western Thailand flowing southward to join the Ping River to form the Chao Phraya	a large natural stream of water (larger than a creek)