Dave:
They are all the same, that means size and weight.
But the brackets makes all of them different, none of them fits right in other places than they originally were meant to go.
That makes for a lot of confusion and a lot of hunting for the exact right ones for you car and for every corner.
As I´ve stated before, it is not hard at all to make or alter the brackets to fit in either place, and the front ones will never show anyway. JMO