on 4 jack systems, the two front ones are connected together, so there is no possibility of torqueing the frame. The two rear jacks are individually controlled. To tilt from side to side, one or the other rear jacks are raised or lowered. To tilt from back to front, you can raise or lower either the front or back jacks.
The 3 jack and 4 jack systems are functionally equivalent. Using a single front jack may save some complexity, but will require a heavier jack.