river vs Argun River

river and Argun River both are nouns.

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

river (noun)	Argun River (noun)
a large natural stream of water (larger than a creek)	a river in eastern Asia that arises in China and flows northeast along the border between China and Russia to become a tributary of the Amur River