Windows Update can't be readily disabled in Windows 10 Home, and the license terms that all users must agree to allow Microsoft to install updates automatically.

The Insider Preview releases of Windows 10 didn't include any way to prevent Windows Update from downloading and installing updates, but it wasn't clear if this was just some quirk of the previews or the long-term plan; Microsoft's previews often have special rules for things like providing automated feedback and hooking up online services, and so this could have been part of that.

Build 10240, released to insiders on Wednesday, changes that. This build is believed to be the release-to-manufacturing build that OEMs will preinstall on hardware, and as such, it contains the finalized settings, license text, and so on.

Windows Update in Windows 8.1 has four options for Windows Update's behavior: download and install updates automatically; download updates automatically but choose when to install them; check for updates but choose when to download and install them; and never check for, download, or install updates. This last option is, obviously, not recommended, but it's there if you really need it.

In Windows 10, the options are cut to two: check, download, install, and reboot automatically; and check, download, install automatically and then choose to reboot. And as Tim Anderson at The Register spotted, the EULA that comes with the operating system (and which again wasn't available during the preview program, as that used a different, preview-specific text) has language that supports this:

Updates. The software periodically checks for system and app updates, and downloads and installs them for you. You may obtain updates only from Microsoft or authorized sources, and Microsoft may need to update your system to provide you with those updates. By accepting this agreement, you agree to receive these types of automatic updates without any additional notice.

(Emphasis ours.)

This would be a notable change in any version of Windows, but it takes on particular significance because of Windows 10's Windows-as-a-Service concept. It's not just security fixes that Microsoft will be rolling out and automatically installing; it's going to be a steady stream of feature updates, too, as Microsoft adds new capabilities and features to its operating system.

While inevitably someone will figure out how to disable Windows Update and block the updates, for the most part this change means that home users of Windows 10 are always going to be running both the most secure version and the version with the most features.

This has immediately raised concerns. Today, if a Windows user finds that an update breaks something that they need, they can generally refuse that update for an extended period. This is particularly apparent with Service Packs; these are both the most likely updates to break things and the easiest to reject. Microsoft continues to deliver security fixes to the operating system both with and without the Service Pack for many months or years after the Service Pack's release.

For Windows 10 Home users, this isn't going to be an option. If a future update breaks something essential, the user is going to be out of luck.

Windows 10 Pro users will have a little flexibility; they'll be able to switch from the mainstream release to the Current Branch for Business (CBB). This will give some control over when updates are deployed. While the CBB will essentially track the consumer release, it will allow feature updates to be held back for some amount of time; Anderson quotes a Microsoft executive saying that companies will have around eight months to prepare for each new feature update. Delay the feature update any further and they'll also be prevented from receiving security updates.

Only Windows 10 Enterprise users will be able to update in a way that resembles the current Windows 8 scheme. By opting for the Long Term Servicing (LTS) branch, Enterprise users will be able to defer feature updates for years, electing to receive only security fixes during that time. Microsoft is pushing most businesses to be on either the consumer release or, at worse, the Current Branch for Business, reserving LTS for mission critical systems that truly need this conservative approach.

What Microsoft is doing with Windows 10 is not unprecedented. Apple for the most part only updates the current version of iOS, forcing iPhone users to accept feature updates if they want to remain secure. Similarly, Google bundles features and security fixes with its Chrome updates. Mozilla does have an LTS version of Firefox that enables businesses to receive security fixes without feature fixes, but even this is limited, with each LTS build being supported for around eight to nine months before being replaced.

It is, nonetheless, a major change in Windows' development and distribution, and the loss of control could give some Windows users the incentive they need to stick with Windows 7 or 8.