Power is sent to the front and rear axles with the centre differential locked, ensuring that a percentage of power is still sent to the forward axles even if a rear wheel is spinning (and vice versa) however the gearing ratio is doubled, increasing torque by more than 2x and reducing speed in each of the gears by the same factor.
In this vehicle setup, the center differential remains engaged, ensuring that power is still delivered to both front and rear axles even if one wheel loses traction (and vice versa). However, the gearing has been adjusted to significantly increase torque while simultaneously decreasing speed in each gear by a corresponding factor.