Upper Avon River vs Avon

Upper Avon River and Avon both are nouns.

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

As nouns, Upper Avon River and Avon are synonyms defined as:

Upper Avon River and Avon: a river in central England that flows through Stratford-on-Avon and empties into the Severn

Other synonyms of Upper Avon River include River Avon, Upper Avon.

Upper Avon River (noun)	Avon (noun)
a river in central England that flows through Stratford-on-Avon and empties into the Severn	a county in southwestern England, named after the river Avon
	a river in central England that flows through Stratford-on-Avon and empties into the Severn
	a river in southwestern England rising in Gloucestershire and flowing through Bristol to empty into the estuary of the Severn