Can you see a difference? I can't see a difference.
On the top left we have Swatch 7 - SSK and K2tog Blended Decreases. Next to it, top right, is Swatch 8 SKP and KSP Decreases. I know the photo doesn't give you a close-up look at the details, but really, even with the swatches sitting right here in front of me I can't see much of a difference between the two. Perhaps the SKP decreases on the right of Swatch 8 look a little straighter than the SSK decreases on the right of Swatch 7, but if so, the difference is so slight I wouldn't choose the SKP. I find the SSK much easier to perform.
On the bottom we have Swatch 9 - K2tog and SSK Full-fashioned Decreases. The idea with full-fashioned decreases is that they are supposed to show in a decorative fashion. Meh. I don't particularly care for it. If I was wanting a more visible/decorative decrease line I would incorporate twisted stitches or a cable of some kind.
Edited April 30, 2007 to add: Evaluators noted on these swatches that the decreases were correctly made, but slightly stretched. They suggested working the decreases on the tips of the needles to minimize stretch.
Some of the decreases are shown in a video HERE. The KSP from the Masters program is the one listed as "KRPR".