No difference whatsoever!
In a 4X4 vehicle, the transmission isn't turning, the transfer case is in Neutral, with the transmission in Park or in any gear (I used to put my Jeep in 6th gear; I put the truck in Park).
In some AWD vehicles (such as a manual transmission Subaru), the transmission is put in Neutral. Automatic transmission Subarus must be towed on a trailer; they can not be towed four down or on a dolly.
SOME rear wheel drive cars that are four down towable can be towed on a dolly. Regardless of what some people say, not all manual transmission rear wheel drive vehicles can be towed four down or on a dolly.
A two wheel drive Jeep is not towable four down or on a dolly unless the drive shaft is removed. Come to think of it, that is how to tow a 4X4 Jeep on a dolly: Remove the rear drive shaft!