Below you can see the front-view size comparison of the Olympus E-PM1 and Leica M Typ 240. The Olympus E-PM1 is clearly the smaller of the two cameras. Its body is 29mm narrower, 16 mm shorter and 8 mm thinner than the Leica M Typ 240.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.