OK, figured it out by looking at the metal plate at the back the pad where the anti-rattle clip rubs up against the metal. The thinner pad was on the outboard side with the wear indicator located at the bottom, same on the other side. I think the inboard pistons are just slightly further out...
While putting my old brake pads back into my front rotors I noticed that one is a tad more worn than the other and don't remember which one goes where.