river vs Klamath River

river and Klamath River both are nouns.

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

river (noun)	Klamath River (noun)
a large natural stream of water (larger than a creek)	a river flowing southwest from Oregon through northern California to the Pacific Ocean