Different foam and core completely. The Platinum shaves a pound off the board weight yet it has even more pop than the regular foam core. Go to
www.ridecwb.com and check out the Platinum core specs. Its pretty impressive and let me tell you it feels dramatically different and personally I much prefer it.
This years Transcend(2006) also comes in the Platinum version. The new 2007 will not be available in Platinum for a few more months, just the foam version.