Should you decide to take a peek inside one of Microsoft’s new stores to get a look at the newly available Microsoft Surface (aka Surface RT), it’s best to make sure that you keep something very straight. Until Microsoft announces that the Surface Pro is available – or at least until it announces a ship date, the only thing you are going to actually see – or that you can currently actually purchase on Microsoft’s online store is the Surface.

You didn’t know about the Surface Pro? Ah…

Some people – especially those of us who are paid to know the difference – can keep the two straight. The larger percentage of the world that may actually buy one in the near term however is not likely to know. Interestingly but not surprisingly, Microsoft itself hasn’t made much noise about the as yet unavailable Surface Pro. In fact, the company – perhaps egregiously - failed to make note of the two different tablets during either their Windows launch event or at a rather cool follow up Surface event the company held a little later in the day with Panos Panay, the general manager of Microsoft's new Surface tablet line (who did a great job of Surface cheerleading at the event).

To understand the differences, let’s look at four specific things: the processors, the operating systems, the displays (important!), the apps, and the keyboards.

Processors up in Arms

The Surface RT that is now available for sale runs on a 32-bit ARM (News - Alert) processor (ARM has announced a 64-bit processor that may appear in 2014 we will note, but for the foreseeable future we are talking 32-bit here). ARM is most emphatically not Intel (News - Alert), but it has an Intel-like presence in the world of mobile devices. When Microsoft first decided to go down the path of a unified Windows 8 ecosystem that would embrace “big iron” (PCs and laptops), tablets and smartphones, the company knew that it would necessarily need to move to support not only Intel but also ARM processors on its tablets.

For a long time the version of Windows that would run ARM-based tablets was known as WOA (Windows on ARM). Eventually WOA was dropped in favor of RT – for which there is no actual meaning! It doesn’t stand for anything at all (RISC Technology, and Real Time – as in the anytime, anywhere nature of mobility may have had some influence, but officially this isn’t the case). That RT designation has now filtered down to the Surface tablet that overtly targets the consumer market, and thus the Surface RT runs on an ARM processor. The 32-bit ARM processor will not support more than 4 GB of RAM (News - Alert).

The Surface Pro directly targets enterprise users, professionals and prosumers, and will run on Intel’s Ivy series multi-core processors. These Intel chips power desktops, laptops and the entire new range of Ultrabooks. They also support huge amounts of RAM, as well as support for a number of Intel hardware-assisted security features.

The Operating Systems

The Surface RT runs Windows RT, an entirely new version of Windows that was written from the ground up to support ARM processors. Many in the media refer to it as a scaled down version of Win 8, but in fact it isn’t a “lite” version of Win 8 but rather a very highly ARM-optimized version of Windows 8. It is designed to be a speed demo on ARM and to take advantage of what the ARM processor offers from a hardware architecture perspective. But – and this is critical – it behaves exactly the same as Windows 8 does on the version of Windows designed to run on Intel’s big 64-bit multicore processors. There is absolutely no difference between the two in terms of either the user interface (UI) or the user experience (UX).

There is one major difference however – and this is the difference that will throw most people off (and don’t be surprised if the Microsoft Store employees aren’t able to clearly articulate this) – Windows RT is not backwards compatible with Windows 7 apps or Win 7’s desktop or how Win 7 apps and the OS generally behave. What this also means is that Windows RT – the Surface RT – will only run new specifically written for Win 8 apps. It will not run Win 7 apps and it never will. We’ll come back to the apps, but let’s return here to the Win RT UI/UX.

The Surface Pro will run Win 8, not Win RT. This means, of course, that all backwards compatibility issues go away for the Surface Pro. Not only will the Surface Pro have the Win 7 style desktop available to it, but it will also support all existing Win 7 apps, such as the current versions of Office.

All “Windows 8” apps – whether running on Win 8, Win 8 RT or Windows Phone (News - Alert) 8, will use the new Windows 8 interface, menu systems, and so on. What was once referred to as the Metro UI, and is now only referred to clumsily as the “Windows 8 Style UI,” (we’ll refer to is as W8UI) is now central to every version of Windows going forward. It is the common denominator across every platform. Win 8 is able to fall back to the Win 7 UI, Win RT cannot – it is much more directly linked to Win Phone 8. But Microsoft’s goal is to move all users forward to W8UI over time and to fully wean users away from any old versions of Windows.

The Surface Displays

Yes, there are going to be some non-trivial differences between the displays of the Surface RT and Surface Pro. Both tablets will sport Microsoft’s ClearType, which is a pixel-rendering technology. We won’t go into any technical details, but Microsoft claims it offers a superior display experience – and though mileage varies from user to user, generally speaking it appears to at least consistently be the case that most users do see improved screen sharpness between Clearype and non-ClearType displays, though how much difference there really is remains debatable.

Independent third party tests have noted that ClearType improves screen sharpness, enough that the Surface RT ClearType display will in fact appear sharper than the iPad 2’s display. The Surface RT has a 10.6 inch, 1366x768 148 PPI screen, which happens to not be very different than the iPad 2’s 9.7 inch, 1024x768 132 PPI screen. ClearType provides the Surface with much more visual clarity than the iPad 2 delivers, though it will not compete in terms of sharpness with the new iPad’s 2048x1536 264 PPI retina display.

The Surface Pro has a 1920x1080 208 PPI screen display that with ClearType may prove to be as sharp the new iPad retina display. Once the Surface Pro becomes available we’ll be able to make more definitive statements about it, but the odds are that the Surface Pro will deliver a very close experience to the Apple (News - Alert) retina display.

The bottom line then is that the Surface RT currently on sale will not get one to the retina quality of the new iPad. But it will more than hold its own.

The Apps

Finally, as the operating system discussion has no doubt already made clear, Windows RT will not run older Win 7 applications. In fact the Surface RT comes complete with its own Win 8 version of Windows Office for this reason. Microsoft needed to make this a reality as the first thing the entire world o Windows users will absolutely want to be able to is keep Windows Office in place and will absolutely not want to have to buy it. At $499 for the basic Surface RT model this actually makes the Surface RT a pretty damn good deal – the new Windows Mail, Excel, Word, PowerPoint and OneNote. Any and all new Windows 8 apps (we include games as apps) will need to come from the new Windows Store.

Win 8 needs to be backwards compatible on many levels – not only with Windows 7 on the consumer front, but with the enterprise, where it will be a critical issue for many years to come. Win 8 will run all Win 7 apps, Office, and any other apps that Win 7 can run that may be older apps. As the Surface Pro runs Win 8 and not Win RT, the backwards compatibility comes with the package. Of course along with that backwards compatibility will also come much heftier price tags than those for the various Surface RT models that are now available for sale. Whether or not those heftier prices will translate to sticker shock or not remains to be seen.

The Keyboards

Microsoft offers two types of keyboards, though both the Surface RT and Pro will be able to use either version. In this one respect, the two tablets are completely compatible.

The Touch Cover and Type Cover magnetically click in and become fully electrically connected. The Touch Cover is truly surprisingly thin and offers a spill-resistant surface and a number of color choices. The Touch Cover provides enough resistance to make typing feel as near to a full keyboard feel as possible, and allows for all finger typing. Microsoft estimates a four day learning curve to do so.

The Type Cover provides a less thin, somewhat heavier cover that delivers a full row of function keys and real keyboard buttons. For enterprise users that may do a lot of typing the Type Cover is probably the better choice. We can anticipate the Type Cover showing up more frequently with the Surface Pro and the Touch Cover being paired more frequently with the Surface RT.

So, there you have it. Now you are ready to hit the Microsoft store – and while you are there you can also provide the sales folks with a few lessons they may need!