Hell has seven names. This is what Aggadat Bereshit says when Malachi promises "the day is coming, burning like an oven" (Malachi 3:19). The rabbis did not flinch from the geography of punishment. Sheol, Abaddon, Death, Pit, the Awful, the Underworld, Gehinnom — seven chambers, seven levels, seven names for the place where the wicked are refined or destroyed depending on how they lived.
But the midrash is more interested in contrast than in punishment. The judgment of the wicked is the context for understanding the reward of the righteous. Israel complained to God: you say "the coming day will burn them," but we have been oppressed for years, judged again and again, calamity upon calamity. Isaiah replies on God's behalf: the fire burns day and night without ceasing, and its smoke rises forever (Isaiah 34:10). The wicked do not escape. They simply wait, while the righteous wait too — but differently.
What separates them? The rabbis return to Abraham's intercession for Sodom: "Will you sweep away the righteous with the wicked?" (Genesis 18:23). Abraham already knew the answer. He was demonstrating — for the record, for all generations — that the righteous and the wicked are not swept away together. The day of burning separates them. The garden of Eden separates them. God's judgment, for all its severity, is not random. It is precise. And that precision is itself a form of mercy — for those paying attention.