both pastors and Bishops (pastors of a diocese) have a set jurisdiction — they have legitimate authority over a parish or a diocese. (A priest, as priest, does not have the same authority. He must be given such power or authority.) Ordinarily they don’t act with authority outside that area of jurisdiction and Episcopal rulings made within their dioceses do not bind outside that diocese. Thus, as a subject of a certain diocese and Bishop I would need to go to my own Bishop for various things. Conversely, the Bishop from a neighboring diocese would not be allowed to act in ways which transgressed the boundaries of my own Bishop, etc even if I traveled within his precincts for a time.
In the case of private vows, however, it is permissible for a Bishop to dispense these even for a visitor to his diocese. He does not need to be concerned about transgressing the jurisdiction of another Bishop in doing so. This could never be done for public vows (for instance, those of a diocesan hermit) made in the hands of another diocese’s Bishop and thus, “accepted in the name of the Church”. Meanwhile, confessors are not allowed to dispense private vows unless they have been given executive power to do so.