Between wool and foam pads, in general, wool pads are considered "cutting" in nature, they also produce less friction induced heat than foam. That is, the fibres of the wool pad "cut" into the paint, removing top layers of paint much more rapidly than foam pads, which do a relatively small amount of cutting but instead rely on greater kinetic friction to do their work.
Compound/ Heavy Cutting Pad (*Yellow) - a harder more dense foam (40 PPI) composition with an abrasive cutting action, for use with a medium abrasive polish, Machine Polish 1 or 2, Swirl Mark Remover, or a Paint Renovator Polish
Light Cutting / Polishing Pad (*Orange) - a mid range, high density foam (50 PPI) composition with a medium abrasive cutting action, for use with a Swirl Mark Remover, Pre-Wax Paint Cleaner, Klasse or Zaino All-In-One, or Autoglym Super Resin Polish
Polish / Waxing Pad (*White) - a softer less dense foam (60 PPI) composition with a light abrasive cutting action, for use with a Swirl Mark Remover, Pre-Wax Paint Cleaner, Klasse or Zaino All-In-One,, or Autoglym Super Resin Polish
Light Polishing Pad (*Black) - an ultra-smooth foam (80 PPI) composition that has very minor abrasive cutting ability, for use with Klasse High Sealant Gloss, Autoglym Extra Gloss Protection, Zanio Z-2 or Z-5 or a Glaze
Finishing Pad (* Red) - this foam (100 PPI) pad has no cutting or cleaning action but is softer foam than the black pad. It should be used for paint burnishing or to apply a glaze or a finessing polish.
Finessing Pad (* Blue) soft enough composition for applying glazes, sealants and liquid waxes or burnishing paint
*These colour identifications are for Lake County Manufacturing (LC) foam pads. There is no common standard used to identify the abrasiveness of foam
There is also a post by TH0001 on the foam pads carried by PAC