AP Racing CP5555 vs. CP5575

These two brake kits are made by AP racing for the M3 CSL (and M3 E46).

CP5555 caliper (pdf) -> link CP5555-1037
CP5575 caliper (pdf)-> link 
CP5575-1004

The first kit CP5555 could not fit to OEM wheels (18" M3, 19" M3 and 19" M3 CSL).
Then AP came up with the CP5575 so as it can fit to the OEM wheels.

The obvious difference is that the 
CP5555 caliper uses 18mm thick pads while the CP5575 caliper uses 17mm thick pads.

Both kits use the same size of disc (356mm x 32mm) and the same disc part number.

I have printed the wheel clearance guides, cuted them and draw them so as we can see the difference.
The difference has to do with the clearance between the caliper and the wheel spokes.
The "diameter" of the CP5555 is not bigger, it's exactly the same.