The article originally appeared in the Jan./Feb. edition of INTERNET TELEPHONY.

When Steven Sinofsky (formerly the guy who ran the Windows team and now the latest guy out of Microsoft (News - Alert)) and his teams set out to build the next version of Windows, Microsoft had some very ambitious plans on the table for the future, and one enormously pressing need: backwards compatibility with all things Windows 7. Lots of people speak about the decline of Windows from the perspective of units sold, but in fact Windows 7 has been a huge success for Microsoft. It is everywhere, and it is enormously stable.

Along with Windows 7 come all of the surrounding platforms that comprise the Microsoft empire – from core enterprise software (Exchange, SQLServer, SharePoint, etc.) to what is also core for both the enterprise and most consumers, Microsoft Office. Much as Microsoft knew that it could get users to switch to Windows 8, Microsoft also knew that it had to preserve the billions of dollars in Windows 7-based investments that enterprises and consumers have made on every other software platform Microsoft delivers.

The dual need to look ahead in a significant way while also looking backwards and remaining fully compatible – and on top of it adding a new and significant mobile platform to the mix as well as having to build out a thoroughly modern touch interface to accommodate today’s emerging hardware mix – was a daunting challenge. The word non-trivial doesn’t really get at the magnitude of that challenge.

Here is what we absolutely believe: Microsoft (and Sinofsky needs to get a lot of credit here) has delivered big time.

To achieve every one of these goals Microsoft had to take an umbrella approach to solving the many problems associated with the overall challenge – which resulted in three distinct versions of Windows:

• Windows 8 (which we like to think of as the mother ship)
• Windows 8 RT for ARM processor-based hardware
• Windows Phone (News - Alert) 8

To understand the differences, let’s look at four specific things: the processors, the operating systems themselves, the user interface and user experience, and the applications.

Processors up in Arms

Most tablets, including Microsoft’s own Surface RT, run on 32-bit ARM processors. (ARM has announced a 64-bit processor that may appear in 2014, but for the foreseeable future we are talking 32-bit here.) The most important thing to know about ARM is that it 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 add support for ARM processors.

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 Windows RT. RT doesn’t actually stand for anything. 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 also filtered down to Microsoft’s ARM-based Surface tablet that overtly targets the consumer market. An important thing to know about the 32-bit ARM processor is that it will not support more than 4 GB of RAM (News - Alert) (ARM won’t be able to support more memory until the 64-bit version emerges).

Microsoft’s Surface Pro and every one of the new tablets, Ultrabooks and laptops that will emerge from Microsoft’s hardware partners that directly target enterprise users, professionals and prosumers on the other hand, will all run on Intel’s Ivy series multi-core processors. These Intel chips not only power the enterprise, but they also support huge amounts of RAM and deliver support for a number of key Intel hardware-assisted security features.

The Operating Systems, the UI and the Apps

The mother ship Windows 8 is the next major version of Windows. It has been built from the ground up with a new Start screen interface that focuses extensively on delivering a 21st century multi-touch- and gesture-based interface. All new Windows apps run from this interface, and all new Windows apps bring with them a different approach to how the user interfaces with applications. Interestingly, Microsoft has actually worked to remove Windows from Windows.

The new interface encourages users to stay within the app and doesn’t allow you to have multiple resizable windows open (though a user can have two apps open on the screen if desired). This is a key change, but of course a user can continue to have as many apps open as might be desired. The touch interface (which also still supports traditional mouse point-and-click operations) makes it simple to move between apps, new Start capabilities that used to be handled through the old Start me, and other capabilities (some of which Microsoft refers to as charms – options that are customizable by developers for their own specific apps, but which must retain a cohesive charms look and feel).

Win 8 also provides that critical full backwards compatibility with Windows 7 and all Windows 7 applications and enterprise backend software. When a user switches to desktop mode, lo and behold, that familiar Windows 7 UI (and for the most part the older Vista and Windows XP UI) suddenly takes over. With one exception – the old Start menu is no longer there.

We don’t have the space to detail the Start menu here, or other issues surrounding the UI, but we’ve covered it elsewhere for those interested in a deeper dive. The new Windows UI and UX were collectively referred to for a long time as the Metro UI (and you will still hear the term used as such) but have since evolved into simply the Windows 8-style UI (we’ll refer to is as W8UI) due to a copyright issue with a German company that already owns the term Metro.

Windows RT is 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 demon 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 multi-core processors. There is absolutely no difference between the two in terms of either the new user interface or the new user experience of W8UI.

There is one major difference, however – and this is the difference that will throw most people off (and don’t be surprised if 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 – and any tablets built on it, including Microsoft’s Surface RT – will only run new apps specifically written for Win 8, which must be purchased through the new Windows App Store.

Win RT will not run Win 7 apps today, and it never will. To ensure that users can continue to have access to Microsoft Office, Microsoft has taken the unusual step of including a Win 8 version of Office as part of Windows RT. 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 8, will use W8UI’s interface, menu systems, and so on. 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 in this respect. 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.

Windows Phone 8 looks and feels and behaves exactly as the mother ship and RT versions of Windows do.

One Cohesive Ecosystem for Tomorrow, Today…and Yesterday

That brings us to today. We have Google’s Android, which will always remain an outlier as far as the enterprise is concerned, and in most cases will remain an outlier in the home as well. There is no connection whatsoever between Android, Apple’s (News - Alert) Mac OS or iOS, or any version of Windows, including Windows 8.

Apple has its own cross to bear on this front, as it still has two separate OS environments, neither of which can handle anything the other does. There is no connection between the Mac OS and iOS. Apple wants to get there, but the odds of it doing so are probably 3 and perhaps 5 years away.

All Microsoft has done is to have (uniquely, it can be said) pulled off an entirely cohesive operating system that spans all modern day devices and yesterday’s software. Windows 8 works cohesively and it works well.

Bash Microsoft all you want, but when the company delivers, it should get the recognition for doing so.