geographical area vs Sub-Saharan Africa

geographical area and Sub-Saharan Africa both are nouns.

Word	Noun	Adjective	Verb	Adverb
geographical area	Yes	No	No	No
Sub-Saharan Africa	Yes	No	No	No

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