Top sirloin is a cut of meat from the loin. Top sirloin steaks differ from sirloin steaks in that the bone and the tenderloin have been removed. The sirloin steak is beef steak cut from the lower portion of the ribs, continuing off the tenderloin from which filet mignon is cut. Of the steaks typically considered to be premium steaks, the sirloin is the cheapest, because the muscles still do quite a bit of work. The sirloin is actually divided into several types of steak. The top sirloin is the most prized of these.  The bottom sirloin in turn connects to the sirloin tip roast, which is generally considered to be a good, if somewhat tough, roast.