Well, ? The basic stuff is similar. Motor, pick-ups, etc.
The PS3 boards have many more finer wires going to different places. The lighting is all for LED in the full PS3 board. They go to a 40 pin connector where the PS2 went to a 12 and a 8 pin.
The stock MTH installed PS3 steam boards are 2 separate pieces. One in the engine (boiler) and one in the tender.
Then there's the PS32......