Penobscot vs Penobscot River

Penobscot and Penobscot River both are nouns.

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

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

Penobscot and Penobscot River: a river in central Maine flowing into Penobscot Bay

Penobscot (noun)	Penobscot River (noun)
a river in central Maine flowing into Penobscot Bay	a river in central Maine flowing into Penobscot Bay
a member of the Algonquian people belonging to the Abnaki confederacy and living in the Penobscot valley in northern Maine