CREATE TABLE table_203_594 (id NUMBER, "canal" CLOB, "length  ( miles ) " NUMBER, "locks" NUMBER, "max length  ( ft ) " NUMBER, "width  ( ft ) " NUMBER, "year opened" NUMBER, "year abandoned" NUMBER, "year restored" NUMBER)

how many more locks does caledonian canal have compared to aberdeenshire canal ?
SELECT (SELECT "locks" FROM table_203_594 WHERE "canal" = 'caledonian canal') - (SELECT "locks" FROM table_203_594 WHERE "canal" = 'aberdeenshire canal')
SELECT (SELECT "locks" FROM "table_203_594" WHERE "canal" = 'caledonian canal') - (SELECT "locks" FROM "table_203_594" WHERE "canal" = 'aberdeenshire canal')