South Florida and North Florida are the two competing sides of the state of Florida that have been at a fairly good equilibrium for the last decade or two: their front is roughly along
Interstate 4. In general, South Florida refers to
Miami,
Ft. Lauderdale,
West Palm, and their suburbs.
Key West,
Jupiter, and other cities in the region are, on rare occasions, tossed into the mix, but generally the idea of South Florida is that it's the hip, liberal, urban, Span-o-phonic side of the state.
North Florida, on the other hand, is represented best by Jacksonville, Pensacola, Gainesville, and Tallahassee, by cows, plantations, and military bases. The coast of the Gulf of Mexico around the Florida panhandle (especially around Panama City) is affectionately known as the "Redneck Riviera."
Tampa and Orlando are sort of in limbo between the two sides, because they have a very strong old-school conservative core that is slowly being pushed out by the same migration from the Northeast that populated South Florida in the first place. Whether they will end up like Miami in twenty or thirty years is pretty much a moot point, since the whole state will have sunk into the ocean by then.