river vs Rhein

river and Rhein both are nouns.

Word	Noun	Adjective	Verb	Adverb
river	Yes	No	No	No
Rhein	Yes	No	No	No

river (noun)	Rhein (noun)
a large natural stream of water (larger than a creek)	a major European river carrying more traffic than any other river in the world; flows into the North Sea