This week I've faced an avalanche of mail about Office 2013 and, in particular, how it differs from Office 365. The licensing details are a bit hard to swallow, but once you see where Microsoft's headed, they're pretty straightforward. More accurately, they're straightforward if you don't read, or don't believe, Microsoft's own misleading and demonstrably inaccurate posts on the topic.

At a very high level, the key difference between Office 365 Home Premium and Office 2013 is rent vs. buy.

An individual who rents Office 365 Home Premium is allowed to install the Office programs on up to five PCs or Macs "in the same household." (Note that Office 365 Home Premium isn't licensed for business/government/nonprofit use.) If one of the computers dies, it's relatively easy to transfer that computer's license to a new machine. The license continues in force for a year, after which the individual needs to renew the license.

An individual who buys Office 2013, on the other hand, receives a perpetual license for the Office 2013 programs. That's very similar to the way Office 2010 works -- except it isn't. Why? Office 2010 has very liberal licensing terms, while Office 2013's terms aren't so user-friendly. With Office 2010, depending on the version, you could install the product on two or three different PCs. With Office 2013, you only get a license for one PC. More than that, the license is tied to that PC -- if your PC dies, for whatever reason, your license expires with it.

I'm waiting for someone to fry their new Surface Pro, return it to Microsoft, and demand that the company replace their copy of Office 2013. If I hear how Microsoft handles that situation, I'll let you know.

There are many permutations and combinations, not all of which are clear. For example, I understand the "one PC, one user" restriction -- but what happens when more than one person uses the PC? Installing Office 2013 puts valid copies of Office 2013 in all of the PC's Windows accounts. Are the other people using the PC not allowed to touch it? And what if you sell the PC?

Australian site The Age has a very thorough rundown of the many additional licensing unknowns.

Here's the rub: I repeated this same basic litany to several people who wrote in with licensing questions, and one of them came up with a Microsoft website that says precisely the opposite of what the license says.

ST pointed me to a Microsoft Canada "Choose Your Office" site where Microsoft states quite specifically that both Office 365 Home Premium and Office 2013 client can be installed on up to five PCs or Macs. "Office on multiple devices/Install Office on up to 5 PCs or Macs and on select mobile devices."

If Microsoft can't get the information right on its own site -- if the licensing terms for a straightforward consumer product are that incredibly complex -- how on earth are customers supposed to figure it all out?

Adam Turner at The Age sums it up this way: "You might think I'm splitting hairs, but if you're going to spend hundreds of dollars on Office, then you need to know whether you've lost your money if your computer dies."

This story, "Microsoft mangles Office 2013 licensing," was originally published at InfoWorld.com. Get the first word on what the important tech news really means with the InfoWorld Tech Watch blog. For the latest developments in business technology news, follow InfoWorld.com on Twitter.

Correction: This blog as originally posted had an incorrect link for Microsoft Canada. The article has been amended.

