By how many points did McAllister improve upon Safran's score?
return McAllister ;return Safran ;return points scored of #1 ;return points scored of #2 ;return number of  #3 ;return number of  #4 ;return the  difference of #5 and  #6
['select', 'select', 'project', 'project', 'aggregate', 'aggregate', 'arithmetic']