CREATE TABLE table_203_630 (id DECIMAL, "rank" DECIMAL, "nation" TEXT, "gold" DECIMAL, "silver" DECIMAL, "bronze" DECIMAL, "total" DECIMAL)

south korea has how many more medals that north korea ?
SELECT (SELECT "total" FROM table_203_630 WHERE "nation" = 'south korea') - (SELECT "total" FROM table_203_630 WHERE "nation" = 'north korea')
SELECT (SELECT "total" FROM "table_203_630" WHERE "nation" = 'south korea') - (SELECT "total" FROM "table_203_630" WHERE "nation" = 'north korea')