South America vs Uruguay River

South America and Uruguay River both are nouns.

Word	Noun	Adjective	Verb	Adverb
South America	Yes	No	No	No
Uruguay River	Yes	No	No	No

South America (noun)	Uruguay River (noun)
the nations of the South American continent collectively	a South American river that arises in southern Brazil and flows south to the Rio de la Plata; the northern section forms the boundary between Argentina and Brazil and the southern section forms the boundary between Argentina and Uruguay
a continent in the western hemisphere connected to North America by the Isthmus of Panama