A super Charger is driven by the engine, normally a belt, a turbo charger is driven by exaust gas pressure. Both work inder the same principle, forced air induction to produce more power. Typicaly, turbo chargers have a bit of a lag before the boost is felt because of the time it takes for the exhaust to get the turbo up to speed and increase the boost.
As for converting a 2X4 to 4X4 I would think it would be more expensive than it would be worth in the long run. With the new Independent Front Suspensions on newer trucks, it's not the same as the old truck that had solid front axles, even on the 2X4 models! The real locker would be much easier and more affordable.
Lift kits abound on the internet, and not knowing the model year of your truck, it's hard to say what's available. Most of the major name brands offer excellent kits for both 4X4 and 2X4 trucks.
Hope this helps a bit...
