Below you can see the front-view size comparison of the Nikon 1 AW1 and Olympus E-PM2. The Olympus E-PM2 is clearly the smaller of the two cameras. Its body is 4 mm narrower, 8 mm shorter and 3 mm thinner than the Nikon 1 AW1.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.