Supercharger or Turbocharger

[Bake]

Another thing is turbo's can offer variable controlled boost by a mechanical dial or computer controlled switch. but with a supercharger you must change belts to change to boots. unless you have an electronic belt tensioner. Also the turbo lag during spoolup where you get no extra boost till it hits set rpms, and the supercharger, as soon as you hit the gas, you get the boost.
but the thing i dont understand is the complete oppsite pressure from the boost you get when you brake with a super. like if you are running wth 8psi of boost and you brake, you get 8psi of vaccume, what does that mean?