I know they are interchangeable but isn't the iPad one different to allow for higher voltage for charging?
there is a slight difference cosmetically on the usb end of the iPad 30pin
It's just a cosmetic difference on the gen 3 cable. The USB end is no longer bevelled. That's it. A friend of mine just bought a 3GS and it came with the new cable.
I am unsure what is different about these cables, but if I use the old Ipod cable plugged in my computer to sync the Ipad it takes hours. If I use the cable that came with the Ipad it takes 5 minutes.
All of the cables are the same going back to the inception of the USB to 30 Pin.