My 2 cents...
Board Press - Out of the rack like a bench press, touch the boards and explode up. Great way to overload. For me a major Triceps lift.
Pins or Rack Press - More difficult for me. Start the move with the bar on the Pins (starting from zero) and press hard, bring down at a full pause with no "bounce". As I mentioned that it is harder for me due to the increased stress on the Delts and overall involvement of the shoulders.
Im no expert by any means and this is just based on my experiences with these lifts.
LOAD YOUR PLATE, LOAD YOUR BAR!
~ Roger Ryan