Below you can see the front-view size comparison of the Olympus TG-870 and Olympus E-M10 II. The Olympus TG-870 is clearly the smaller of the two cameras. Its body is 7mm narrower, 19 mm shorter and 19 mm thinner than the Olympus E-M10 II.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.