[Coda]

From what I've heard you should do the regular ending before you do the genocide ending, because the genocide ending does a bunch of fourth-wall-breaking stuff (that I won't spoil because it's awesome, but will significantly impact your ability to do another playthrough).

I understand the difference. Pacifism is more about nonviolence than it is about not killing. It's choosing to take the peaceful option, and not liking the feeling of doing violent things. Things not ending up dead is mostly a side effect -- a highly desirable one, yes, but sometimes being nonviolent LEADS to things ending up dead.