It's telling that AirPower wasn't released alongside iPhone 8 and X. It's got to be different enough that Apple couldn't just build a Qi compliant charger which any cheap no name brand can do. The fact that it can charge multiple devices without a very specific placement on the mat seems to suggest that it's a longer range charger, although that range could be measured by the confines of the mat to a central power distribution coil.
My guess is that Apple makes this worth it by making AirPower actual wireless charging. Build it into Macs to charge keyboards and mice a couple of feet away. Build it into iPads to charge Apple Pencil nearby. Plugged in Macs would also be able to charge nearby iPhones on the desk. If the distance is measured in yards, rather than inches or feet, it's likely that the new AirPorts will have AirPower built in to charge devices scattered around a room.
If AirPower lives up to its name, it'll be truly wireless and the wait will have been worth it.