Ob River vs Ob

Ob River and Ob both are nouns.

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

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

Ob River and Ob: a major river of western Siberia; flows generally northward and westward to the Gulf of Ob and the Kara Sea

Ob River (noun)	Ob (noun)
a major river of western Siberia; flows generally northward and westward to the Gulf of Ob and the Kara Sea	a major river of western Siberia; flows generally northward and westward to the Gulf of Ob and the Kara Sea