What is the difference between the number of matches where SC Ganguly played as a Captain and those matches where he played other roles?
SC Ganguly refers to Player_Name = 'SC Ganguly'; played as a Captain refers to Role_Id = 1; played other roles refers to Role_Id > 1; difference refers to SUBTRACT(COUNT(Role_Id = 1), COUNT(Role_Id > 1))
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'