Normal Box & BSP Scales?

Can someone please tell me why the normal box and BSP boxes have different scales? like on a normal box I can set the height ( z ) to 2.0, yet if I use that same number for a BSP box, it doubles in size, anyone know why this is? can I change it so both match?

Not sure why they are different scales to start with but I changed the scale of the mesh box to 2 and it was the same scale as the bsp box.

Then I changed the scale of the bsp box to 2 and the mesh box to 4 and they were the same. (they are inside each other in the screenshot but still the same size)

You can also manually change the shape of the bsp box if you go into the geometry editing tab, this lets you select the vertices and position them however you want.