Actually there is a little more to it. All wheel drive is a broad term. In fact, some AWD vehicles are not AWD all the time. Some AWD vehicles are permanent 4-wheel drive.
Traditionally 4WD spoke of a vehicle that had to be engaged manually by the driver with a mechanical shifter. Today we have electric switches that handle these functions, but other than pick-ups, most SUVS have moved away from this. The terminology has been blurred. Permanent AWD means there is some power applied to all four wheels at all times. There may be a permanent ratio or one that can be fluid depending on speed, loss of traction, etc.
Regarding Audis they are not all the same. The lower end versions use a transverse mounted engine and are therefore FWD biased. Other versions use a longitudinal mounted engine and are rear biased.