Below you can see the front-view size comparison of the Olympus E-M5 II and Panasonic S1R. The Olympus E-M5 II is clearly the smaller of the two cameras. Its body is 25mm narrower, 25 mm shorter and 52 mm thinner than the Panasonic S1R.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.