Calipers have more flexibility. The adapter that connects the caliper to the spindle accounts for the increased diameter of the rotor.

Basically, there are two possible caliper types you could have, one is held to the adapter via pins (called pin type), the other sets in a machined guide in the adapter (called sliders).

Once you figure out how they are mounted then you can potentially figure out the donor, I say potentially because piston diameter will also be a factor,