Normal Call (color defined by the options):
If your programmer is empty and you press the Pool Button once, you'll select alle the fixtures that can use the effect. The second press will run the effect in your programmer.
Fast Call (buttons will have a dark red color):
Again beginning with an empty programmer. One presson a pool button will immediately run the effect for all possible fixtures. Still running in the programmer.
Pool Playback (the buttons will have a magenta color) :
Now you can press the pool buttons and the effect will run in the pool as if it was running on an executor.