Below you can see the front-view size comparison of the Fujifilm X-T1 and Fujifilm X-T10. The Fujifilm X-T10 is clearly the smaller of the two cameras. Its body is 11 mm narrower, 7 mm shorter and 6 mm thinner than the Fujifilm X-T1.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.