Which publisher created more superheroes: DC or Marvel Comics? Find the difference in the number of superheroes.
DC refers to publisher_name = 'DC Comics'; Marvel Comics refers to publisher_name = 'Marvel Comics'; if SUM(publisher_name = 'DC Comics') > SUM(publisher_name = 'Marvel Comics'), it means DC Comics published more superheroes than Marvel Comics; if SUM(publisher_name = 'Marvel Comics') > SUM(publisher_name = 'Marvel Comics'), it means Marvel Comics published more heroes than DC Comics; difference = SUBTRACT(SUM(publisher_name = 'DC Comics'), SUM(publisher_name = 'Marvel Comics'));
SELECT SUM(CASE WHEN T2.publisher_name = 'DC Comics' THEN 1 ELSE 0 END) - SUM(CASE WHEN T2.publisher_name = 'Marvel Comics' THEN 1 ELSE 0 END) FROM superhero AS T1 INNER JOIN publisher AS T2 ON T1.publisher_id = T2.id