Navigating “back,” like going from the "Now Playing" pane in the music player to the "Album" pane for example, also differs between the two devices. The iPhone and many other smartphones use a button to go to a previous pane in an application. In the above example, the iPhone (the right-hand image) has a "back" button in the upper-left corner of its screen. On the Pre, however, you make a "back" gesture by swiping right to left on the Pre’s gesture pad (the space immediately below the screen).
This threw me off, not only because I was expecting a button, but because it wasn't immediately obvious in which direction I was supposed to swipe. On both the iPhone and the Pre, when you flip through photos, for example, you swipe from left to right to flip to the previous photo in an album, so I assumed the gesture-pad area would work the same way; instead, you must use the reverse direction.
Other gestures, such as scrolling and zooming in or out on images, are the same on both devices. Also, the Pre has a nifty, quick tutorial when you first use the phone to help you get acquainted with some of the gestures.