Just reading up on more of it, and the iPad updates are odd. The iPad Air 2 is a proper upgrade over the Air. A7 to A8X processor change, Touch ID, better camera, etc.

The Mini 3 has three differences from the Mini 2. Touch ID, storage options, and a gold color choice. No processor or other technical spec bump. It's a strange lineup with 3 mini models available. Non retina, or two retina choices with a $100 premium for a touch ID sensor.