These are listed on the Europe site
http://www.casio-europe.com/euro/emi/wk3200/
http://www.casio-europe.com/euro/emi/wk3700/

From what I see there's 20 more sounds, 20 more patterns, AND GET THIS...., instead of 2.0mb of flash rom-an increase to 32mb's of flash rom Holy Crap! the Samples you can load into that... There's also an IDES CD Rom Included with the unit. It looks like the colors have changed a little too.

Squeak
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GEAR: Yamaha MOXF-6, Casio MZX-500, Roland Juno-Di, M-Audio Venom, Roland RS-70, Yamaha PSR S700, M-Audio Axiom Pro-61 (Midi Controller). SOFTWARE: Mixcraft-7, PowerTracks Pro Audio 2013, Beat Thang Virtual, Dimension Le.