It's semantics really. Your average off roader with 4WD has a transfer case which has the necessary bits to provide power to all 4 wheels in two ratios (and some allow low ratio power just to the rear wheels as well). AWD is when the transfer case is bypassed in favour of a differential or torque converter in the middle, which usually require no input from the driver.
AWD is different from full time 4WD though, since a full time 4WD vehicle will still have a transfer case, but with a torque converter or limited slip differential in the middle and 2WD funtionality removed (otherwise it wouldn't be "full time" 4WD, lolz).
Again, this is all comes down to semantics since manufacturers use all kinds of jargon when describing what is essentially the same principle. If I were you, I wouldn't spend anymore time thinking about it, because really it's all the same.