Upper Avon vs river

Upper Avon and river both are nouns.

Word	Noun	Adjective	Verb	Adverb
Upper Avon	Yes	No	No	No
river	Yes	No	No	No

Upper Avon (noun)	river (noun)
a river in central England that flows through Stratford-on-Avon and empties into the Severn	a large natural stream of water (larger than a creek)