Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_204_621 ( id number, "no." number, "date" text, "tournament" text, "winning score" text, "margin\nof victory" text, "runner(s)-up" text )

### Question ###
what is the difference of winning score between the san antonio texas open and the dallas centennial open ?

### Accurate SQL ###

SELECT ABS((SELECT "winning score" FROM table_204_621 WHERE "tournament" = 'san antonio texas open') - (SELECT "winning score" FROM table_204_621 WHERE "tournament" = 'dallas centennial open'))