Difference between 'Social Activists' and 'Social Justice Warriors'

Of course the extreme position of the Social Justice Warrior, if taken to it's logical conclusion, would be to cut off the legs of the offender.  As we can see, they are already attempting to send those that suffer from the terrible contagious disease of "white privilege" to the back of the bus.  Of course, just the first step to tossing them under the bus!