river vs Columbia River

river and Columbia River both are nouns.

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

river (noun)	Columbia River (noun)
a large natural stream of water (larger than a creek)	a North American river; rises in southwestern Canada and flows southward across Washington to form the border between Washington and Oregon before emptying into the Pacific; known for its salmon runs in the spring