geographic region vs Sub-Saharan Africa

geographic region and Sub-Saharan Africa both are nouns.

Word	Noun	Adjective	Verb	Adverb
geographic region	Yes	No	No	No
Sub-Saharan Africa	Yes	No	No	No

geographic region (noun)	Sub-Saharan Africa (noun)
a demarcated area of the Earth	the region of Africa to the south of the Sahara Desert