Most significantly, Windows RT devices will not run existing Windows 7, Vista, and XP applications, but only new "Metro" ones created with the new Windows runtime WinRT APIs. Windows RT devices will only be able to install applications from the new online Windows Store, which on the day prior to the Windows 8 launch only had several thousand applications. In fact, browser makers Google and Mozilla have complained that only Internet Explorer 10 will have full access to Windows RT system resources. Windows 8 PCs and tablets will not face these architectural restrictions.
One element potential buyers may find compelling is that Windows RT devices will include a version of the new Office edition at no extra cost called Office Home & Student 2013 RT. It will include Word, Excel, PowerPoint, and OneNote, but not Outlook, and will provide what Microsoft calls "a complete Office experience." However, in what could turn off enterprises, this Office version isn't licensed for business use, requiring that organizations purchase commercial use rights or own a commercial license to Office 2013 suites. Windows RT also lacks several IT management features that Windows 8 does have.
Microsoft plans to make its own Microsoft-branded tablets called Surface. There will be one for Windows RT and another one for Windows 8.
Attempting to address another area where it is perceived to be lagging, Microsoft designed Windows 8 to be tightly integrated with SkyDrive. Microsoft's goal is to make the cloud storage service a "single drive" available across all the devices people use, giving them "instant, secure and private access to their files" and letting them share those files with others.
As of tomorrow, when Windows 8 and Windows RT begin to ship, their fate -- and Microsoft's -- is in the hands of consumers and enterprises.