re: How many different regions are in the south?

A lot depends on what type of subregions you want to talk about. Are we talking about cultural, geographic or geologic? Are we talking about areas that can include large sections of multiple states or areas that are contained within a state?

Like Georgia has three major geographic/geologic regions - the mountains, the piedmont and the coastal plain.

Some areas (Gulf Coast) can be considered geographic as well as cultural.

Just some terms I will throw out and let people assign them where they feel are best.

Cotton Belt
Black Belt
Wiregrass
Lowcountry
Delta
Appalachia
Gulf Coast