The regular formula is for plastic products and lightly damaged bright metal. The "M" version adds a special metal refinishing pad which can restore severe bright metal surface damage - like the iPod's bright metal back panel. Not for use on iPod mini, painted or anodized surfaces. Both versions include Optex application and polishing cloths.
You can purchase the Ice Creme solution for $20.95 and it includes 2 1 oz. bottles of polishing compounds and 2 application/polishing cloths. The Ice Creme "M" is available for $25.95 and includes the same items as the regular solution but with the addition of a bright metal finishing pad.