Below you can see the front-view size comparison of the Fujifilm X-T2 and Fujifilm X-T1. The Fujifilm X-T1 is clearly the smaller of the two cameras. Its body is 4 mm narrower, 2 mm shorter and 2 mm thinner than the Fujifilm X-T2.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.