Below you can see the front view size comparison of Sony RX10 III and Sony RX10. Sony RX10 is clearly the smaller of the two cameras. Its body is 4mm narrower, 6mm shorter and 25mm thinner than Sony RX10 III.
Sony RX10 III vs Sony RX10 - Front View
Sony RX10 III vs Sony RX10 - Top View
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.
Camera Size Comparison
Select Two Cameras for Size Comparison