The most notable difference between the X20 and X30 as seen from the front is the lack of an optical viewfinder. You still rotate the lens to power the camera on.
Change in top controls
The exposure compensation dial now goes up to +/- 3, increased from 2. The mode dial has also changed: no more movie mode, since there's now a dedicated record button; added Filter and Panorama modes; and the custom slots have changed name from "C" to "SP".
The tilting, higher-resolution display is a welcome update from the X20, which had a low-resolution fixed version.
Streamlined back and EVF
In addition to replacing the optical viewfinder with an electronic one, Fujifilm redesigned both the controls and the layout for the X30. There's no more macro button, and the AE-lock button is now in a better position where it can be reached with your right thumb. The other buttons down the left side of the X20 -- playback, white balance and drive mode -- now sit in more traditional locations on the right. It also drops the vertical dial and replaces the horizontal jog dial with a more traditional one.
No changes underneath
The tripod mount is still well-situated for swapping cards or a battery while on a tripod.
The Fujifilm X30 has USB, Micro-HDMI, and a mic input.