Microsoft has been called late to the party for not offering Microsoft Office for the iPad, other tablets, and smartphones. The truth is, Microsoft does make quite a few different versions of Office for mobile devices, although they aren’t full versions of Office.

There are several different versions of Microsoft Office for different versions of Windows, and then you have Office Mobile, Office 365, and Office Online. Each has different features and even different payment structures.

We’ll start with Microsoft’s own tablet and smartphone platforms here, as they have the most feature-complete versions of Office. As a “devices and services” company, Microsoft is clearly trying to use their Microsoft Office service to push their devices.

Windows 8 and Windows RT – Full Microsoft Office, Mostly

Using Office is simple on Windows 8 tablets. You can purchase the full desktop version of Microsoft Office and use it on your Windows 8 tablet, just as you’d use it on a Windows 8 laptop. Office only runs in desktop mode, so you’ll have to use your tablet’s desktop to take advantage of it. It isn’t the ideal interface for a touch screen, but it is the full version of Microsoft Office that you’d use on a desktop PC.

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Most Windows 8 tablets don’t actually include Microsoft Office, so you’ll have to pay for it separately. Some Windows 8 tablets do — 8-inch tablets will include Office, and some 10-inch tablets like the ASUS T101 also include Office for some reason. Other tablets, like Microsoft’s own Surface Pro, don’t come with Office.

Windows RT tablets do include a free version of Office, but it’s a bit limited. For example, macros aren’t supported at all. That said, the version of Office that comes with Windows RT devices is almost the same as the full version of Office for Windows 8, and it’s included for free.

Windows Phone – Office Mobile

Windows Phone comes with a free version of Office known as Office Mobile. Unlike the versions of Office Mobile for iPhone and Android phones, Office Mobile for Windows Phone is completely free to use and doesn’t require an Office 365 subscription.

Of course, Office Mobile is a simplified version of Office for mobile phones. It’s designed so you can view your Office documents and perform some basic editing on the go, not to function as a complete productivity solution.

iPhone and Android – Office 365

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Microsoft now provides “Office Mobile for Office 365 subscribers” apps for iPhone and Android, which you can install from Apple’s App Store or Google Play. Office 365 is Microsoft’s subscription service for Microsoft Office. You pay $100 per year and you gain the ability to download the latest desktop versions of Office for your Windows and Mac PCs. You also get additional OneDrive (formerly SkyDrive) storage space and the ability to use the Office 365 apps for iPhone and Android. These apps let you create and edit documents stored in your OneDrive storage

You do need a subscription to use these apps, so you can’t just buy the apps once and use them forever. They’re also nowhere near being full versions of Microsoft Office — they’re simplified smartphone apps, not serious productivity solutions.

iPad and Android Tablets – Office 365 or Office Online

The Office Mobile for Office 365 apps were clearly designed for smartphones. These fairly simple apps aren’t the feature-rich versions of Microsoft Office you’re familiar with on desktop computers. There’s no way to natively use the full-featured versions of Office on iPads or Android tablets You can attempt to use the Office Mobile for Office 365 subscribers apps on iPad and Android tablets, and you’ll be able to use the simple mobile interfaces. But it’s certainly no substitute for Office on Windows or Mac OS X.

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In the past, Microsoft has also recommended using Office Online in a web browser on your tablet to use a more desktop-like interface. Office Online (formerly known as Office Web Apps) is a browser-based version of Microsoft Office that’s available inside OneDrive (formerly SkyDrive). It’s not as powerful as the full desktop version of Office, but it has a similar interface and its interface may be better suited to a tablet.

Better yet, Office Online is completely free on any platform, so you can use Office without spending a dime — even on your Windows PC — as long as you’re fine using a simplified version within a web browser.

Realistically, most tablet users looking for a solid productivity solution will probably be better off using an alternative office suite, such as Apple’s iWork for iPad, Google’s QuickOffice, or something else that natively supports tablets.

Remote Desktop Solutions

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You can also look into remote desktop solutions. You could install Microsoft Office on a Windows PC or Mac and use remote desktop software to access your desktop from a tablet or smartphone. A company that wants to provide Office on iPads could consider setting up a remote desktop server workers can connect to. It’s not as good as a solid local office app, but it is a way to get the full version of Microsoft Office on an iPad, Android tablet, or any other device.

When it comes to other laptop platforms, Microsoft also provides a full desktop version of Microsoft Office for Mac OS X. It’s included as part of the Office 365 subscription service, or you can buy a boxed copy. On Chromebooks, Linux PCs — and yes, even Windows PCs and Macs — you can use Office Online to use Microsoft Office inside your web browser for free.

Image Credit: Maria Elena on Flickr, Kārlis Dambrāns on Flickr