Huge difference

SELECT * FROM gallery2 WHERE topic_id="593522" UNION SELECT * FROM gallery2 WHERE topic_id="105710" UNION SELECT * FROM gallery2 WHERE topic_id="715356" UNION SELECT * FROM gallery2 WHERE topic_id="278638" UNION SELECT * FROM gallery2 WHERE topic_id="1307441" UNION SELECT * FROM gallery2 WHERE topic_id="1614355" UNION SELECT * FROM gallery2 WHERE topic_id="1074929" UNION SELECT * FROM gallery2 WHERE topic_id="1609183" UNION SELECT * FROM gallery2 WHERE topic_id="599365" UNION SELECT * FROM gallery2 WHERE topic_id="725876" UNION SELECT * FROM gallery2 WHERE topic_id="211809" UNION SELECT * FROM gallery2 WHERE topic_id="828776" UNION SELECT * FROM gallery2 WHERE topic_id="1479702" UNION SELECT * FROM gallery2 WHERE topic_id="99923" UNION SELECT * FROM gallery2 WHERE topic_id="1530521" UNION SELECT * FROM gallery2 WHERE topic_id="1382320"