Tombigbee River vs Tombigbee

Tombigbee River and Tombigbee both are nouns.

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

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

Tombigbee River and Tombigbee: a river that rises in northeastern Mississippi and flows southward through western Alabama to join the Alabama River and form the Mobile River

Tombigbee River (noun)	Tombigbee (noun)
a river that rises in northeastern Mississippi and flows southward through western Alabama to join the Alabama River and form the Mobile River	a river that rises in northeastern Mississippi and flows southward through western Alabama to join the Alabama River and form the Mobile River