river vs Upper Avon

river and Upper Avon both are nouns.

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

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