When you play the 'standard rules’ game mode, strict rules state that the longest sequence you can move during a single operation is equal to the number of empty cells plus one. This number doubles for every empty tableau available (notice though that when moving the cards to an empty tableau, then that tableau is not counted). At Master level, the longest sequence of cards has an additional card beyond what counted by the above rule.

When you play the ‘relaxed rules’ game mode, there is no limitation to the length of a movable sequence of cards which makes the gameplay easier; however, you score less points :)