Database: book_publishing_company
Question: Calculate the average level difference between the Marketing editors hired by the US and non-US publishers?
SQL: SELECT (CAST(SUM(CASE WHEN T1.country = 'USA' THEN job_lvl ELSE 0 END) AS REAL) / SUM(CASE WHEN T1.country = 'USA' THEN 1 ELSE 0 END)) - (CAST(SUM(CASE WHEN T1.country != 'USA' THEN job_lvl ELSE 0 END) AS REAL) / SUM(CASE WHEN T1.country != 'USA' THEN 1 ELSE 0 END)) FROM publishers AS T1 INNER JOIN employee AS T2 ON T1.pub_id = T2.pub_id INNER JOIN jobs AS T3 ON T2.job_id = T3.job_id WHERE T3.job_desc = 'Managing Editor'