It can be the same if you'd like. If cooking to tender (and not shy of tender) a shorter rest 40-50 min is all you need for resting. You can go longer though. Remember that you'll likely see significant residual cooking after pulling the meat from the cooker. Factor that in so as not to take the butt too far along in the cooker as it will continue to cook during resting, especially if tightly foiled and coolered. Not often a big deal with butts; it is with briskets.