Microsoft Windows 8 vs. Windows RT

That fact isn't evident at first glance. Microsoft gave both very similar user interfaces. Both have the touch-friendly, tiles-based Start screen (what used to be called Metro) and, when doing simple tasks, their "look and feel" is essentially identical. Each can be used for the tasks most people do every day: Internet access, email, and working with Microsoft Office files.

Apples and Oranges

However, at heart these two operating systems are profoundly dissimilar, as they were created to run on two very different processors. This affects many aspects of devices running them.

Windows 8 is the latest generation in Microsoft's long-running series of operating systems. It runs in x86 chips from Intel and AMD, and will run third-party software written for previous versions (Windows 7, Windows Vista, etc.).

Windows RT, on the other hand, uses ARM-based processors. Because of this, it has no backward compatibility with older Windows software. All apps have to be written anew for this new platform. And so far, there's not a huge selection.

Has Microsoft Gone Crazy? Crazy Like a Fox

It's likely some are scratching their heads at this point. What is the point of releasing a version of Windows that can't run Windows apps?

It comes down to this: the full version of this operating system isn't well suited to powering a tablet that can compete with the very successful Apple iPad.

Windows 8 is very powerful, but it needs correspondingly powerful hardware to run. The x86 processors that it needs draw far more current than ARM-based ones do, giving devices much shorter battery lives. Its code also takes up a lot more space, requiring more storage capacity.

To see how that plays out in the real world, the least-expensive version of the Microsoft Surface running Windows RT has 32GB of storage and starts at $500. The upcoming version of this tablet with Windows 8 Pro starts at 64GB of storage and will sell for $900.

And Microsoft has already admitted that the Windows 8 version is going to have half the battery life of the Windows RT one, even though this model will have a bigger battery (and be correspondingly larger).

The Surface Pro will have an Intel "Ivy Bridge" Core i5 processor, not one like the Atom "Clover Trail" that has been designed to be less power hungry. It's possible other tablets running this operating system will have longer battery lives, but it's unlikely they will come close to what's offered by tablets running ARM-based chips, as these sip power, not guzzle it.

Striking a Different Balance

Apple's iPad has been successful by offering users just enough -- the features most people use most of the time, in a great-looking device that has excellent performance and an immense battery life.

Windows RT was created to do the same thing. Tablets running it can be affordable and allow users to access the Web, keep up with social networking, watch video, and send/receive email. And it's not entirely consumer oriented -- it comes with a version of Microsoft Office, and not a "dumbed-down" one either.

But it isn't for everyone. People who want the full power of Windows 8 can get a tablet running it. This will give you access to truly vast array of third-party business and consumer software that's been created for Windows over the decades, not just a smattering that has been released for Windows RT so far. Just be aware, there are drawbacks: shorter battery life and higher cost.

Want more? Microsoft has a page called "Help Me Choose" that does a side-by-side comparison of the Surface RT and Surface Pro. While not a direct comparison of Windows 8 Pro and Window3s RT, it's a good way of seeing how the differences will work out in real products.