I do understand it.
The iPad Pro doesn't run a full OS like the MS Surface. There may some overlap in consumer audiences for both, but no one is buying the iPad Pro to replace their laptop like Surface users are.
I think it's more likely Apple would add touch to their laptops if they wanted to compete directly against the Surface.
MacBreak Weekly's podcast coverage of the IPad Pro mentions somone talking to Tim Cook, during his surprise NY store visit, and asking him directly if the iPad Pro would steal sales from the Apple laptops. Tim Cook responded by saying he thought only a small share would do that and that he would continue to need to use his laptop and the iPad.
That tells me that Apple isn't challenging the same Surface audience that wants a full OS, to buy an iPad Pro instead.
I think there's room for different devices for different users. I don't look at this as iPad Pro or Surface Pro. And apparently neither Does Tim Cook, as he included MS Office people to demo at the Apple Event on the iPad Pro.