No difference in surface configs between surfaces that should be very difficult to drive on, vs ones that are hardened, and or smoothed in material components.
A Hardened Clay/Mud Airfield should be relatively smooth in comparison to an unimproved farm field.
A unimproved field should be quite bumpy to drive over but have some level of traction reduction compared to the hardened clay/mud.
A sandy beach should have very poor traction and top speed considerations in comparison to an unimproved field and or a hardened clay runway.
All terrain types should not be equal for traction nor top speed considerations.