SELECT
    MEMBER_ID AS ID,
    CASE
        WHEN ABS(SCORE1 - SCORE2) >= ABS(SCORE2 - SCORE1) THEN (SCORE1 - SCORE2) 
        WHEN ABS(SCORE2 - SCORE1) >= ABS(SCORE1 - SCORE2) THEN (SCORE2 - SCORE1) 
    END AS DIFF
FROM
    CONTEST_RESULTS
WHERE
    SCORE1 - SCORE2 >= 20 OR
    SCORE2 - SCORE1 >= 20
ORDER BY
    DIFF DESC,
    ID DESC