Sculpting with displacement maps lets you:
The low resolution model can be optimized for animation and have a different topology from the high resolution version. You extract the displacement map from the high resolution source model to the low resolution target model (even if it has different topology) so the displacement map can be correlated to the UVs on the low resolution model. Mudbox supports the extraction of displacement maps on models with UVs that exist outside the 0-1 range.
Troubleshoot Sculpt Model Using a Displacement Map