Its completely different, if you stand at an angle and play the ball and it goes sideways then its incorrect ptb as acting half already has edge since he has already taken a step to side to retrieve it..if he deliberately just steps over ball to try and get a quick ptb its incorrect ptb, penalty, but if you attempt to play it and just don`t lift foot high enough, but do touch the ball with foot, you have attempted to play it right..therefore scrum.