CREATE TABLE table_204_320 (id DECIMAL, "rank" DECIMAL, "nation" TEXT, "gold" DECIMAL, "silver" DECIMAL, "bronze" DECIMAL, "total" DECIMAL)

how many more total medals did china win over japan ?
SELECT (SELECT "total" FROM table_204_320 WHERE "nation" = 'china') - (SELECT "total" FROM table_204_320 WHERE "nation" = 'japan')
SELECT (SELECT "total" FROM "table_204_320" WHERE "nation" = 'china') - (SELECT "total" FROM "table_204_320" WHERE "nation" = 'japan')