CREATE TABLE table_204_336 (id NUMBER, "operators" CLOB, "named trains" CLOB, "destination" CLOB, "year begun" CLOB, "year discontinued" NUMBER)

what is the difference -lrb- in years -rrb- between when the royal blue began and the year the crusader began ?
SELECT ABS((SELECT "year begun" FROM table_204_336 WHERE "named trains" = 'royal blue') - (SELECT "year begun" FROM table_204_336 WHERE "named trains" = 'crusader'))
SELECT ABS((SELECT "year begun" FROM "table_204_336" WHERE "named trains" = 'royal blue') - (SELECT "year begun" FROM "table_204_336" WHERE "named trains" = 'crusader'))