CREATE TABLE table_204_681 (id NUMBER, "2011 rank" NUMBER, "2010 rank" NUMBER, "2009 rank" NUMBER, "2008 rank" NUMBER, "2007 rank" NUMBER, "company  ( country ) " CLOB, "2011 arms sales  ( us$ m. ) " NUMBER, "2010 arms sales  ( us$ m. ) " NUMBER, "2009 arms sales  ( us$ m. ) " NUMBER, "2008 arms sales  ( us$ m. ) " NUMBER, "2007 arms sales  ( us$ m. ) " NUMBER, "arms sales as share of company's total sales  ( % )  , " NUMBER)

what is the difference of the amount sold between boeing and general dynamics in 2007 ?
SELECT ABS((SELECT "2007 arms sales (us$ m.)" FROM table_204_681 WHERE "company (country)" = 'boeing') - (SELECT "2007 arms sales (us$ m.)" FROM table_204_681 WHERE "company (country)" = 'general dynamics'))
SELECT ABS((SELECT "2007 arms sales (us$ m.)" FROM "table_204_681" WHERE "company (country)" = 'boeing') - (SELECT "2007 arms sales (us$ m.)" FROM "table_204_681" WHERE "company (country)" = 'general dynamics'))