What is the difference in Windows Defender and Microsoft Security Essentials?

I have Windows 7 with IE 11 and I use Microsoft Security Essentials for virus and malware protection. I sometimes see reference to using MSE and then Windows Defender. My question is what is the difference between these two applications? Aren't they both the same? Do I need both?

Thank you,



 Ahoy Thomas,

Microsoft tends to name, rename, and repurpose old names for its software, which is how we end up with Outlook Express, Office Outlook, and Outlook.com, all different products targeting different users (and that's just half of it).

When it comes to security software, the same holds true: the bottom line is that if you are using Windows XP, Windows Vista, or Windows 7, Microsoft Security Essentials is a free anti-virus and anti-spyware security suite that you can download for free.

If you are using Windows 8 / 8.1 or Windows 10, you don't need, and in fact cannot, download MSE for your computer: that's because as of Windows 8, Microsoft has bundled it into the operating system - no download or install required on your end.

The confusion? MSE, when talking about Windows 8 and later, is now called "Windows Defender" (which would have been fine, had there not been another security software made by Microsoft, called Windows Defender, which was not an anti-virus!)

As often, Microsoft tends to confuse us with name changes and line extensions (like Hotmail vs. Outlook), so here's the breakdown for Microsoft Security Essentials and Windows Defender:

"Windows Defender", anti spyware tool before MSE Microsoft acquired a third-party anti-spyware product in 2004, first renaming it "Microsoft AntiSpyware", and later "Windows Defender": this wasn't an anti-virus, but an anti-spyware solution.

It was also available as a free download for Windows XP, and shipped included into both Windows Vista and Windows 7.

◾In 2009, Microsoft released MSE ("Microsoft Security Essentials"), which was an anti-virus software, whose functionality crossed over Windows Defender: this is why Windows Defender is disabled once you install MSE in Windows 7 and earlier versions.

MSE isn't bundled with any version of Windows, but it's available as a free download from Windows XP through 7.

Windows Defender running in Windows 8 / 8.1 / 10 For the first time, Microsoft shipped an anti-virus package built into the operating system with Windows 8: it is called "Windows Defender", and does basically the same thing as MSE.

 You won't be lost using Windows 8 / 8.1 / 10 if you are familiar with MSE.

So, to keep things clear, Windows Defender for Windows 8 and later is mostly the same thing as Microsoft Security Essentials for Windows 7 and earlier!


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Last updated June 11, 2020 Views 47,804 Applies to: