Why does Windows 8 come with two versions of Internet Explorer, both of which are named Internet Explorer 10? Well, probably because Windows Store apps don't run on the Windows desktop, at least not without a third-party utility making it happen. As a result, the Modern UI gets its own Metro-style, touch-optimized, full-screen version of IE, while the desktop gets a traditional version designed for mouse/keyboard use.
Confused yet? There's more. Add-ons that work in desktop IE, such as browser extensions and toolbars, don't work in the touch-friendly Modern version. And tabs work differently in the two versions too. Oh, and if you select another program, such as Google Chrome, as your default browser in Windows 8, you'll see only the desktop version of IE 10. Yikes! Perhaps this all made sense in the early planning stages of Windows 8 (after a few beers), but from a usability perspective, it's a train wreck. Windows Blue is a good opportunity to set things straight.