It's not the width, or any dimension of the pads, they are the same, the difference is the top of the back plate, the FA77, has two ' ears ' where the pine go through and a large spring that presses down on the pads the back plate on the FA77 dips down to just a few mm's above the friction material, the FA18 has two holes for the pins, but the back plate goes straight across, with a small notch in the middle .
Well found something interesting, I went to Dennis Kirk motorcycle parts and they have pictures of the FA77 and FA18 pads and they are the same, no difference, even have two different part numbers on the back side of the plate .
I wonder if the springs on the ATE calipers are not available and you can use the set up from the Brembo calipers on them

Need to go to the garage and check this out !!!!

I went to the EBC application site, there is no listing for R65's with ATE calipers .
There is an application for the R45 with ATE calipers and the pads are FA57 .
I'm sure these would be applicable to the R65 .
So, the FA77's will work on a Brembo caliper !!!!