The Mishna says that when the collapsed house belonged to reuven and the collapsed attic belonged to shimon, we have to do our best to determine whether who most likely deserves the whole bricks and who deserves the broken bricks. Rashi in the Mishna explains that if the house collapsed due to a faulty foundation so that the bottom brick broke and the upper bricks came down on top of them, we can assume that the broken bricks belong to reuven who lived on the bottom, and the whole bricks belong to shimon who lived on the top. But if the wall of the house fell like a stick, so that the upper bricks came crashing down, we can assume that the broken bricks are from shimon's attic, whereas the whole bricks belong to reuven. However, Rashi in the gemara (d.h. reisha) explains differently than he does in the mishna. Rashi in the gemara says that if the foundation gives way, the upper bricks belong to shimon who lives on the top (regardless of whether they are broken or whole). It comes out that when the foundation gives way, rashi in the mishna implies that reuven who lives on the bottom would get the broken stones, whereas rashi in the gemara implies that he would get the lower stones even if they are whole?