"Racing Schools" are gonna spend a lot of time on actual racing strategies, passing, drafting, presenting, and because of that I heard they don't teach you as much how to drive a car fast and safe. You'll be driving a quasi-race car with open wheels on race rubber which will perform absolutely nothing like your car.
"Driving Schools" are often referred to as HPDEs (High Performance Driving Experience) and put an instructor in YOUR car and make sure you understand what your car is capable of, with your current setup, on street tires. They'll have you dial it up as you get comfortable with it. All passing is done on straights and only when the pass-e gives you a point-buy. There are no timing devices, and the only purpose is to have a blast, be smooth, and learn the limits of your car and yourself.
So, once I've mastered every aspect of my driving in my car, then maybe I'll attend some "racing schools" if I feel I can perform in some amateur racing series. Til' then, the $2500 I'd spend for 2 days at Skip Barber can pay for all of my HPDEs this year plus some very sweet brake upgrades.
Someone correct me if I've missed something.