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_311 ( id number, "rank" number, "nation" text, "gold" number, "silver" number, "bronze" number, "total" number )

### Question ###
what is the difference between the total number of bronze medals won by the united states and west germany ?

### Accurate SQL ###

SELECT (SELECT "bronze" FROM table_204_311 WHERE "nation" = 'united states') - (SELECT "bronze" FROM table_204_311 WHERE "nation" = 'west germany')