South America vs Guiana Shield

South America and Guiana Shield both are nouns.

Word	Noun	Adjective	Verb	Adverb
South America	Yes	No	No	No
Guiana Shield	Yes	No	No	No

South America (noun)	Guiana Shield (noun)
the nations of the South American continent collectively	a mountainous tableland in northern South America; extends from Venezuela into Guyana and northern Brazil
a continent in the western hemisphere connected to North America by the Isthmus of Panama