The P60 Race Stocks are built in the traditional Volkl fashion- full wood core wrapped in fiberglass, all in a titanal sandwich. The P60 Racings are built in a 'new-school' Volkl construction similar to that of the Supersports. They still use a full wood core, but the profile is different - somewhat scalloped - to fit in with their double grip concept. The "ridges" are separate pieces of wood, and they are all wrapped in glass. Titanal is also used, but I suspect the sheets are a little thinner than they are on the Race Stocks. The P60 Racings are available only with the Motion rail system while the Race Stocks are only available flat.
The performance difference is remarkable. The Race Stocks are what they should be - strong and unforgiving. They really aren't that versatile for most skiers in a non-racing situation. The P60 Racings have about 95% of the stability and grip of the Race Stocks, but are significantly more versatile for a high performance skier. The P60 Racing is one of Volkl's best models - it rivals the Supersports in stability and versatility. It's a shame that it's virtually ignored.
The 5 Star and 6 Star are have identical constructions - the 5 is just a little softer. They both have a similar construction to the P60 Racings, but without the titanal. The Superspeed is a much different animal. It's essentially a WC Race Stock GS ski with a 70 mm waist. Lots of titanal in there.