How many more people died in the crash of American Airlines Flight 11 than United Airlines Flight 175?
return American Airlines Flight  11 ;return United Airlines Flight  175 ;return people that died in  the  crash of #1 ;return people that died in  the  crash of #2 ;return number of  #3 ;return number of  #4 ;return the  difference of #5 and  #6
['select', 'select', 'project', 'project', 'aggregate', 'aggregate', 'arithmetic']