AWD: All wheels can get power and differentials are used for turning, etc. Therefore, if one wheel has no traction (snow / mud / ice) and slips, it draws all the power and you can't move without restoring traction.
4WD means all wheels spin at equal rates; there are no differentials. Therefore even if one wheel slips, the other three will pull you forward. Great for off-road but sucks for higher speed driving with turns.
AWD: All wheels can get power and differentials are used for turning, etc. Therefore, if one wheel has no traction (snow / mud / ice) and slips, it draws all the power and you can't move without restoring traction.
4WD means all wheels spin at equal rates; there are no differentials. Therefore even if one wheel slips, the other three will pull you forward. Great for off-road but sucks for higher speed driving with turns.