Thames vs Thames River

Thames and Thames River both are nouns.

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

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

Thames and Thames River: the longest river in England; flows eastward through London to the North Sea

Other synonyms of Thames include River Thames.

Thames (noun)	Thames River (noun)
the longest river in England; flows eastward through London to the North Sea	the longest river in England; flows eastward through London to the North Sea