Question: What is the difference between the number of matches where SC Ganguly played as a Captain and those matches where he played other roles?
SQL: SELECT SUM(CASE WHEN T3.Role_Id = 1 THEN 1 ELSE 0 END) - SUM(CASE WHEN T3.Role_Id > 1 THEN 1 ELSE 0 END) FROM Player_Match AS T1 INNER JOIN Player AS T2 ON T1.Player_Id = T2.Player_Id INNER JOIN Rolee AS T3 ON T1.Role_Id = T3.Role_Id WHERE T2.Player_Name = 'SC Ganguly'