User blog comment:Duncan Crook/Want To Become a Rollback?/@comment-2110162-20101003030956/@comment-28390087-20101220153037

Rollback and Undo are almost different.
 * 1) Rollback can rollback to the way it was and the edit the previous user made, is not seen at all
 * 2) Undo returned the page to normal but leaves a trail in history