Nan vs Nan River

Nan and Nan River both are nouns.

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

As nouns, Nan and Nan River are synonyms defined as:

Nan and Nan River: a river of western Thailand flowing southward to join the Ping River to form the Chao Phraya

Nan (noun)	Nan River (noun)
a river of western Thailand flowing southward to join the Ping River to form the Chao Phraya	a river of western Thailand flowing southward to join the Ping River to form the Chao Phraya