In windows 7, windows defender is a built in the anti-malware program used to supplement any installed antivirus program in the system.Avast is an antivirus, we all know that.Can We Compare Windows Defender with Avast? In this article, I will show you the performance of windows defender and avast in different security sectors. Now, which one you should choose? Windows Defender or Avast? If you are looking for an honest windows defender vs avast comparison, then follow me. Introduction: Windows defender is a good antivirus for windows 10, but as a concerned user, you should check the other free antiviruses as well, Huh? Avast is one of the most common names in this field.