Question: Find the difference between the number of female senators and representatives born between 1930 to 1970.
SQL: SELECT SUM(CASE WHEN T2.type = 'sen' THEN 1 ELSE 0 END) - SUM(CASE WHEN T2.type = 'rep' THEN 1 ELSE 0 END) FROM historical AS T1 INNER JOIN `historical-terms` AS T2 ON T1.bioguide_id = T2.bioguide WHERE T1.gender_bio = 'F' AND strftime('%Y', T1.birthday_bio) BETWEEN '1930' AND '1970'