Windows Defender is purely anti-spyware.Windows Defender detects and removes known spyware only. It is not designed to protect against the full breadth of malicious software, and specifically does not prevent viruses, worms, Trojans, and other malicious
software from infecting your machine.
Microsoft Security Essentials has all the capabilities and features of Windows Defender along with a complete anti-virus protection.MSE was designed to replace Windows Defender.
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