Here, I will do my best to examine the differences between bad and evil. In Nietzsche’s Genealogy of Morals, there is a clear differentiation that is made between pre-slave-revolt bad and post-slave-revolt evil (for if there wasn’t, wouldn’t Nietzsche simply have left them both as bad?).
First, I will define both the bad and the evil so that we do not misinterpret each other. Prior to the slave revolt in morality, the bad were composed of people who were more topically “bad.” That is, these people were ugly, poor, weak, etc. After these slaves revolted, they became the new good, while the old good became evil. Evil in this sense involved an internal necessity for values (as opposed to an external necessity), self-affirmation, good being determined first and evil being determined as an afterthought, and generally those who were beautiful, wealthy, and strong. While these definitions are meek, they will stand as a mutual understanding throughout the rest of this post.
To begin, the qualities that identified what was bad were qualities that weren’t necessarily feared by the good. The noble spirit was not ever threatened by what was bad; rather they simply were better and insurmountable. While the nobles may have distanced themselves from the bad, there is something particularly special about this idea of fear. To clarify what I mean, I will begin talking about the evil that was the good in light of fear. The evil, which is present today, is something that is arguably frightening to what is now good. In being a part of the herd, I find myself in the present ‘good’ category. This means, according to Nietzsche, that I am nay saying and life-denying. As a part of the good, I can’t help but feel a bit frightened by those who may fall into the evil category. These are people who enact physical revenge and are life-affirming. I am afraid that these people, if I encounter them, will dominate me in any sort of interaction, but I do not want to see it that way. This denial forces me to assign to them the name ‘evil.’
In essence, the main difference between the two (at least from what I can tell) is fear. The pre-revolt-good did not fear the bad, but the post-revolt-good most definitely is afraid of the evil. Perhaps this fear stems from us, the herd, acknowledging (subconsciously or consciously) that we are in fact weak and unable to make life-affirming decisions. But we cannot externalize these thoughts, because if we do the noble spirit will dominate us again.