Diffs are typically the same, the half shafts on the back are different as the "inner" oil seal is relocated inside the stub axle and runs directly on the half shaft. Later cars had single peice half shafts but with the later matric bolts and a thinner end cap, though some earlier ABS cars had 2 peice half shafts. The ABS sensor goes on the "dry" side of the hub with a ring bolted inside the disk.
On the front the swivels are different, there is no phosphour bronze bush supporting the inner halfshaft because the cv and outer drive shaft are one peice, thus supporting the inner driveshaft too.
The top swivel bearing is replaced with a RAILKO style bearing (like the Defender) to accomodate the ABS sensor which reads the splines cut into the CV joint itself, this is the sensor you need to blank or fit Defender swivel pins.
The stub axle is different, the inner bearings on a Disco/RRC are roller bearings instead of another phosphour bronze one plus the "inner" oil seal is again inside the stub axle.
The hubs are different, because of the lack of oil seal, and I'm not sure if the wheel bearings run further apart so I don't know if the hubs are interchangeable. The disks and callipers use the same mountings though so AFAIK are interchangeable.
In truth I'd say the Disco ABS axles are more like your current Defender axles than non-ABS Disco axles in terms of how they work inside.
