In my recent writings about Windows 8, I’ve tried to stress that this new system is a mobile OS and not an evolution of Windows 7. That’s because the new Metro-style apps in Windows 8 are mobile apps, not traditional desktop applications. The difference may seem subtle, but it isn’t. And bridging this conceptual divide is key to your understanding and using Windows 8 effectively.

Rather than blather about the future, I’ll just use two examples to highlight the difference between Metro-style apps—which are mobile apps—and the traditional desktop applications we all know and love: SkyDrive and email.

SkyDrive

Windows 8 comes with a Metro-style SkyDrive app and you can, of course, install a SkyDrive desktop application (which also works in Windows 7). These are two completely different animals, and a perfect example of the difference between a mobile app (Metro) and a desktop application.

Consider the SkyDrive app for Windows Phone, iPhone/iPad, or Android. These mobile apps provide a front-end to the content you’ve stored in SkyDrive, and you can browse around your SkyDrive folder structure, open files, and so on. But the SkyDrive mobile app isn’t persistent, and it doesn’t “sync” the contents of your SkyDrive storage to the device. It’s just a live view of that data. If your device is offline, the content is inaccessible.

The Metro-style SkyDrive apps works exactly like that, because it is in fact exactly like that: A mobile app that provides you with a live view of your cloud-based data. If you only use the Metro-style SkyDrive app in Windows 8, you will not be able to sync the contents of your SkyDrive to the PC or device, and you will not be able to access that content while offline.

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Yes, this the SkyDrive app's offline experience. 

Because Microsoft makes Windows 8 and Windows Phone, it does provide those platforms with some additional functionality that is not available on other mobile platforms like iOS or Android. For example, in Windows 8, Microsoft has integrated your SkyDrive storage into the system-level file picker, allowing any Metro app to open files from, or save files to, SkyDrive … assuming of course you’re online.

The SkyDrive desktop application is different. This application allows you to seamlessly sync your SkyDrive-based content with your PC’s local file system. Unlike the mobile app, the SkyDrive application thus provides you with offline access to your content, and if you add, delete, or change files in there while offline, they’ll be automatically synced to the cloud—and to any other connected PCs—once you’re online again.

Email

Email is another classic example of the divide between Metro’s mobile apps and the desktop applications most people are familiar with. And while traditional email solutions like Microsoft Outlook and Windows Live Mail (and its predecessors Windows Mail and Outlook Express) do of course connect to online email sources, including modern email sources based on IMAP or Exchange ActiveSync (EAS), they were originally designed with offline usage in mind, where users would permanently download content from the server and store it on their PCs. Mail, Windows 8’s Metro-style email app doesn’t work this way, and does not support old-school email management methods at all. Instead, it works exactly like the mobile email apps on iOS, Android, and Windows Phone: It syncs content with modern email sources only.

This difference is important to understand, especially if you’ve spent the past several years maintaining a local Outlook PST file that contains all of your email, contacts, and calendar information. That’s the old way of doing things, where you centralized your email (in this example) storage around a single PC. There are great reasons not to do this—a hard drive failure could cause irrecoverable data loss, for starters—but that’s not the full story. As we move towards more mobile devices, we also give up storage. So while your PC could have terabytes of disk space, a typical mobile device has 32 GB or 64 GB of storage or less. (And yes, this includes Windows 8 and RT tablets too.) Centralizing email storage on the PC/device doesn’t make sense.

What does make sense is centralizing this data—and your contacts and calendars, too—in the cloud, in an account such as Hotmail/Outlook.com, Google (Gmail/Google Calendar), Exchange (on-premise, hosted, or via Office 365), or similar. When you do this, your email can be synced to any client—a Windows 8 PC, a Windows RT device, a tablet, or a smart phone—automatically, so you’ll always have the most recent data wherever you need it. And if the drive on that PC dies, or you lose your smart phone, no worries: Everything is up in the cloud. Just sign in again on a different PC or device and you’re good to go.

The Mail app in Windows 8, like all other Metro-style apps, is a mobile app. It works much like the Mail app on Windows Phone in that it connects only to modern email sources (basically Exchange ActiveSync accounts like the aforementioned Hotmail/Outlook.com, Google, and Exchange types mentioned above, or IMAP), and it syncs only a limited amount of data to the device (two weeks by default) to save on disk space, while providing live access to your complete email store when you’re online. Unlike the SkyDrive app mentioned above, Mail does work offline by providing a limited set of capabilities for such usage. But in that sense, again, it works just like the Windows Phone Mail app does. It’s a mobile app.

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The Mail app lets you sync content from your online account, but not download it permanently.

Remember: Metro is mobile

Someone asked me today via email how one might ago about migrating their Outlook-based data to Windows 8’s respective Metro-style apps (Mail, People, and Calendar). The answer is … you can’t. Instead, you must migrate your data from Outlook to a connected email service of some kind (again, Hotmail/Outlook.com, Gmail/Google Calendar, Exchange—on-premise or hosted, or Office 365--or similar). Once that’s done, you just connect to the email service from Mail, People, and Calendar. (You only have to do this once, as the three apps are connected and use the same accounts.)

Explaining how you might make such a migration may be a good topic for a future article. But for now, the important point is this: Windows 8 is as much a mobile platform as is Windows Phone, the iPhone, or Android. It’s just that Windows 8 also includes the classic PC-based desktop environment we know from previous Windows versions too. If you are more comfortable using traditional PC applications, Windows 8 lets you do that. But the new Metro apps platform in Windows 8 is all mobile, and it works just like other mobile platforms.