There is no iPad Pro 10.5 or 10.9. There is iPad Pro 11 and 12.9. The difference between them is size and that's about it. There did used to be a 10" iPad Pro but that was before the 11" came out. The difference between those is that the older smaller one had a Home Button on it and the new one does not. The new iPad Air has 10.9" screen and there is quite a few difference between the Air and the Pro. However, the older iPad Air was way different from the new one. That one used the 1st Gen Pencil and the new one uses the 2nd Gen Pencil. It also had a Home Button and the new one does not. It had a completely different chassis and design. Just like every time they update, there is a faster processor in the new one as well. The Power button also has the finger print scanner on it instead of in the Home Button as there is no Home Button on the new one.