I had another thought that came into my head, Whats the difference between AWD and 4WD?Does AWD have 4 wheels pulling fulltime, and 4WD can be switched to 2WD? Or is there really no difference between them?

 

You got it right! except the AWD supposedly selects automatically the wheels that need to provide traction.

 

4WD, better known as 4x4, when engaged applies equal power to each of the 4 wheels. A good design like GM or Ford, Dodge, also have posi-traction, which means that even when any of the wheels are in a slippery surface, the rest still get their 25% power per wheel. With these 4x4's, one can disconnect, by removing the driveshafts, either the front or the rear and still get underway. 4x4 is used at low speeds, usually under 55 mph and often in conjunction with "Low Range" which can limit speeds to under 10 mph.

A cheap 4x4 design .. ie . many foreigns, specially w/o posi-traction .. take the path of least resistance, meaning the slipping wheel could get 100% of the power while the rest get zero% and you go no where. I will leave personal opinions out.

The AWD, at least the Cadillac gives you no choice and all the wheels have power at all times. The computers decide what percentage of power to direct to either the front or rear wheels based on road conditions and speed. Should you be in a slippery road, like snow or ice, the computers sense that, and direct most of the power to the front wheels. On a normal road, you get equal 50/50 rear to front. It can be used at ANY speed - the Italian cars can and do 250 mph with it and so do our Cadillacs. At such speeds, one needs all the traction you can get and AWD provides it. The CTS-4 is a WORLD CLASS machine raising the bar.

AWD is better than 2WD for off-road, the 4x4 is better than AWD or 2WD for off-road conditions.

maybe not done? gotta run .. may come back and edit ..

 

GM AWD a long time ago it was called Full Time allows all wheels to have power whether on dry pavement or sand. Old full time had high & low range. AWD is a single speed and its not really designed for "4 wheelin". They can have planetary gears or viscous (limited slip) clutches within transfer cases. Down side is if one axle is hung many times you're stuck till help or a wench arrives. Most late model transfer cases do not have planetary gears they lock both driveshafts and they're are not designed for 4WD operation on dry pavement. They're still differential gears in the axles. Vehicles both axles open can get stuck easy, as soon as 1 front and 1 rear wheel loose traction. If you have limited slip it will engage both wheels of that axle. Most 4WD or AWD have limited slip rear axles very few have both front and rear. Auto4WD when selected computer monitors for slippage, when slippage is detected, engages front axle. Jeep and Hummer offers NV242 transfer case which allows for AWD and 4WD and with electric lockers in front and rear diff.s all 4 wheels have power.