Question: Find out the difference between the number of publishers who released the games on the PS3 and X360.
SQL: SELECT COUNT(CASE WHEN T2.platform_name = 'PS3' THEN T1.game_publisher_id ELSE NULL END) - COUNT(CASE WHEN T2.platform_name = 'X360' THEN T1.game_publisher_id ELSE NULL END) FROM game_platform AS T1 INNER JOIN platform AS T2 ON T1.platform_id = T2.id