Below you can see the front-view size comparison of the Olympus XZ-2 iHS and Nikon 1 J5. The Nikon 1 J5 is clearly the smaller of the two cameras. Its body is 15 mm narrower, 5 mm shorter and 16 mm thinner than the Olympus XZ-2 iHS.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.