Git reflog is a per-ref log of its previous values. JJ operation log is a whole-repo atomic journal of changes. It's much more powerful. You can e.g. undo a change deep in history that already had multiple descendant branches (that jj rebased for you).
Since jj snapshots the commit you're editing a lot, you can often even jj undo an accidental edit to a just-created file that in git would have still been uncommitted.
Since jj snapshots the commit you're editing a lot, you can often even jj undo an accidental edit to a just-created file that in git would have still been uncommitted.