Below you can see the front-view size comparison of the Fujifilm S5 Pro and Fujifilm S3 Pro. The Fujifilm S5 Pro is clearly the smaller of the two cameras. Its body is 1mm narrower, 22 mm shorter and 6 mm thinner than the Fujifilm S3 Pro.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.