Microsoft is getting even more serious about differentiating between Internet Explorer and Project Spartan, the new browser built for Windows 10. When Windows 10 ships later in 2015, IE11 will not use Edge, the new rendering engine built for Project Spartan. Instead, IE11 will remain powered by the Trident engine--exactly as it is in Windows 8.1.
Microsoft's original plan was to let both Internet Explorer and Project Spartan use Edge. The two browsers would also be able to fallback to Trident for sites using Microsoft's legacy web technologies. After feedback from developers, however, Microsoft is drawing a clear line between the two browsers: IE11 is for legacy sites (mostly enterprise Intranet sites and web apps) while Project Spartan is for the modern web.
The impact on you at home: Drawing a clear distinction between IE and Spartan can only be good for users. If you want a browser that embraces the modern web and offers advanced features like a "reader mode" and Cortana integration, then Project Spartan is the browser you want. Those who need access to Microsoft's legacy technologies can stick with IE11.
Further reading: Windows 10: The best tips, tweaks, and tricks
Despite the new distinction, you're able to let Edge power IE11 right now in Windows 10, if you perform some tweaks. For users who need specific legacy technology, however, Microsoft said that enabling Edge in IE11 makes the browser behave differently in Windows 10 than it did in Windows 8.1. That's far from ideal in a browser designed for legacy compatibility with older sites and intranet portals.
Microsoft isn't wasting any time in separating the two browsers. The next update to Windows 10 will dump Edge support for IE11. At the same time, the update will include an early build of Project Spartan, Microsoft said.