The inner pads’ backing plate has two ears on the top of the pad that match up the the brake caliper pistons. The outer pad has a chamfer are the top. The pads have the same ears that rest in the lands of the caliper bracket. It is possible to install the caliper over the mixed up pads and install the guide pins.
If pads are in the mixed up, when the brakes are applied the caliper could come in contact with the inside of the wheel.
Special thanks to Ford technician and YouTuber FordTechMakuloco for making this great video: