Thank you Umbrapolaris,
Excuse me I am a beginner.
I was thinking maybe one of them implement faster some new blocking elements, or some new features which could help, or even some of them already have some others blocking elements then others, so they complete each other, for a more intensive protection.
Could they even have conflicts one with each other?
Tell me please, If they could not "interfere" one with each other in a bad way, could they do something wrong to the functionality of the system or other programs, more than they will use more hardware resources?