Ouse River vs River Ouse

Ouse River and River Ouse both are nouns.

Word	Noun	Adjective	Verb	Adverb
Ouse River	Yes	No	No	No
River Ouse	Yes	No	No	No

As nouns, Ouse River and River Ouse are synonyms defined as:

Ouse River and River Ouse: a river in northeastern England that flows generally southeastward to join the Trent River and form the Humber

Other synonyms of Ouse River include Ouse.

Ouse River (noun)	River Ouse (noun)
a river in northeastern England that flows generally southeastward to join the Trent River and form the Humber	a river in northeastern England that flows generally southeastward to join the Trent River and form the Humber