River Trent vs Trent River

River Trent and Trent River both are nouns.

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

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

River Trent and Trent River: a river in central England that flows generally northeastward to join with the Ouse River and form the Humber

Other synonyms of River Trent include Trent.

River Trent (noun)	Trent River (noun)
a river in central England that flows generally northeastward to join with the Ouse River and form the Humber	a river in central England that flows generally northeastward to join with the Ouse River and form the Humber