@1.
Lancia 4WD has higher ratios and less ground clearance than Panda 4x4.
Lancia has vacuum- or electric-switchable rear drive, Panda has manual.
Lancia has free-wheeling hubs (also vacuum- or electric) in rear wheels, Panda doesn't. Some italian Panda 4x4 fans add free-wheeling hubs for their Pandas, but they are manual (more durable), especially made for Panda.
Lancias are more "luxurious" inside (velour etc.)
Lancias 4WD are much cheaper in Italy than Pandas 4x4.
So I think for serious off-road work Panda is better, for on-road Lancia is better.
@2.
Body of 4x4 and 4x2 Pandas is basically the same, only with higher and different suspension.
Sutjeska