Below you can see the front-view size comparison of the Olympus E-M10 and Olympus E-M10 III. The Olympus E-M10 is clearly the smaller of the two cameras. Its body is 3mm narrower, 2 mm shorter and 4 mm thinner than the Olympus E-M10 III.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.