Allroad is using longer longer control arms (to reduce the effects of the long suspension travel).

I would assume by moving the inner pivot point more towards the center (so AR using 'inner' holes in the subframe, A6 uses outer holes), thus keeping the track width (location of wheel/bearing) the same (also since same tie rods, uprights and upper control arms are used).

With this in mind: are A6 and AR using the same length CV Axles (or same CV axle)? If not, what are the differences?