10.5 is Pro, 9.7 isn't.
As opposed to the guy above, I bought 12.9 one and I must say with pencil it literally saves my back. I am a college student and before iPad I hat to carry backpack filled with frikkin' binders and laptop on top of that and eventually it simply got unbearable. After I got iPad Pro and Pencil - that's literally the only thing in my backpack now, because I don't need anything else.
On top of that submitting written assignments and taking notes became insanely more productive, as I don't need to scan paper shit to PDF and what not and just can toss it from the app directly as PDF to wherever I need and have that and all my work and notes synced across just about any device I own.
It is simply a great convenience.
As a whole I am not a huge fan of Apple and this is the only Apple device I own, but it's damn good I have to admit.