Penobscot River vs Penobscot

Penobscot River and Penobscot both are nouns.

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

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

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

Penobscot River (noun)	Penobscot (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