Below you can see the front-view size comparison of the Olympus TG-4 and Olympus E-PL8. The Olympus TG-4 is clearly the smaller of the two cameras. Its body is 3mm narrower, 1 mm shorter and 7 mm thinner than the Olympus E-PL8.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.