New screens
Both of the new models sport better screens than the earlier devices, although the color hasn't changed significantly. Resolution is still 160 x 160, to maintain compatibility with the thousands of third-party software titles currently available. In low light conditions where you might need to use the backlight on earlier models, both of the newer models are easier to read without using the backlight. They are both also easier to read in bright light conditions -- the screens have much less glare, and can be read more easily at more different angles than previous Palm devices.

There are now two backlight modes, normal and inverted, both of which can be toggled using a shortcut. Normal backlight mode leaves the background dark and illuminates the text, and inverted backlight mode illuminates the background, leaving the text dark. I have to admit to being confused by the terminology here. Inverted mode is more like the backlighting found on earlier Palm devices, which seems more "normal" to me.

By the way, people with earlier backlit Palm devices can use LightHack to provide both backlight modes, or use LightHack to set the default backlight mode for the new models to inverted mode (which will seem normal). If you have to reset your Palm IIIx, or Palm V, and you're not running LightHack, the backlighting will default to normal mode until you execute a shortcut. You'll need a copy of HackMaster to use LightHack.

New processor
Both models are based on a new processor, the Motorola DragonBall EZ, rather than the DragonBall found in earlier models. The DragonBall EZ offers some behind-the-scenes advantages to Palm's hardware designers, most notably smaller size. Its main advantage to the Palm IIIx or Palm V user is lower power consumption, which means even longer battery life. Also, according to Julie Strietelmeier who runs The Gadgeteer (at http://www.the-gadgeteer.com), the new devices are approximately 12% faster than the older ones, at least based on the one prime number sieve benchmark test she ran.