This factoid is interesting, while the iPad can only run one program at a time, the Surface can run multiple programs...
"Delta does stand out as unique, though, for choosing the Microsoft Surface. The Surface 2 tablets will run Jeppesen’s FliteDeck Pro app, which was built for Windows 8.1. The app provides pilots with all of the research and reference materials normally found in the flight bag, with the added benefit of real-time access to relevant information as conditions change.
The Delta press release explains how some of the unique aspects of Windows 8.1 influenced the decision to go with Surface 2: “With the Windows RT 8.1 operating system, pilots will be able to open two applications side-by-side, offering, for example, the opportunity to assess weather information alongside proposed flight paths.”
Edit: Link to Delta
Delta to equip 11,000 pilots with Microsoft Surface 2 tablet devices - Sep 30, 2013