CREATE TABLE table_204_821 (id NUMBER, "speed [km/h  ( mph ) ]" CLOB, "train" CLOB, "type" CLOB, "location" CLOB, "date" CLOB, "comments" CLOB)

what is the difference in speed number of the fastest and slowest trains in km/h ?
SELECT MAX("speed [km/h (mph)]") - MIN("speed [km/h (mph)]") FROM table_204_821
SELECT MAX("speed [km/h (mph)]") - MIN("speed [km/h (mph)]") FROM "table_204_821"