Microsoft CEO Satya Nadella Robert Galbraith/Reuters On Tuesday, Microsoft announced Windows 10 S — a new, streamlined version of the Windows 10 operating system designed to take on Google's low-cost Chromebooks.

Microsoft promises that Windows 10 S brings boosts to battery life, security, and performance over the standard Windows 10 operating system.

The tradeoff for those gains, says Microsoft, is that Windows 10 S users can only install apps from the Windows Store. For $49, you can upgrade from "S" to Windows 10 Pro and install whatever you'd like, with Microsoft warning that the switch will likely undermine your battery life and system speed.

This raised some red flags among the tech world.

The existing Windows 10 Pro operating system already has a setting that lets you turn off the ability to install non-Windows Store software. And so some, like Andreessen Horowitz investor Benedict Evans, had a question: Is Microsoft giving people a crippled operating system and charging them $49 to fix it?

I took the question to Microsoft, asking if there were any core, technical differences between Windows 10 S and Windows 10 Pro, beyond just that setting.

While Windows 10 S and Pro sport the same interface — important, given how familiar people are with the Windows interface — a Microsoft spokesperson says that under the hood, there's one really big difference.

In Windows 10 S, apps are "containerized," or isolated from one another, to make 100% sure that they're not making changes to the operating system or installing anything behind the scenes, and that it doesn't keep running in the background when you close it. It's a similar approach to how Apple thinks about the security of iPhone and iPad apps.

Microsoft Surface Laptop, shipping on June 15th for $999, is the flagship device for Windows 10 S. Jeff Dunn/Business Insider

This app containerization is much different than the almost-anything-goes approach that Windows has used historically, including in Windows 10 Pro. That's why, I'm told, if you go from Windows 10 Pro to Windows 10 S, you actually lose the ability to go back to Pro without wiping your machine. It's a one-way switch caused by technical constraints, Microsoft says.

There are a few other, smaller changes. For instance, on Windows 10 S, the default save location is in OneDrive cloud storage, so a student can pick up their work again on a different computer. There are also a few little tweaks to the Start menu, and some changes to how it integrates with IT department administrative systems.

It's the containerization aspect that really sets it apart, technically speaking, though. So by Microsoft's reckoning, that's why it's not just Windows 10 Pro with a student-friendlier skin and a more restrictive model.