Re: How does the new iPad Pro differentiate itself from the MacBook Pro
I don't see the harm in actually answering a fair question. Each has its own OS and apps, for me as a MBP Retina owner I am actually going to upgrade my 2014 MBP Retina to a new 5k iMac and get the iPad Pro to be used as my mobile laptop replacement. There are going to be trade offs in not have a laptop but since most of my mobile use is geared towards web, office and productivity, and not laptop based use I feel its a solid trade off.
I can add something like the LeefBridge Leef Mobile Memory and add additional expandable storage which is something Apple has failed to do. This will give you Laptop level storage and flexibility.
If what you are going to do requires apps that are OS X specific and no iOS comparable is available then I would say stick with the MBP.