Shurhold's Wool Buff Magic Pad is a bit more aggressive and should be used for heavier oxidation. It needs to be fluffed and cleaned out regularly.
The Foam Buff Magic Pad is easier to work with and it doesn't have to be cleaned as often. The trade off is a less aggressive pad that takes a bit longer to work compounds in with.
In most cases the Foam Buff Magic Pad is aggressive enough.