Comes with a bigger screen and better battery life than the original. Figures cause I just purchased my HTC Touch Pro about 2 months ago. Great phone, I use it constantly to listen to podcasts during my commute.
The Diamond2 gets a screen upgrade, from 2.8in to 3.2in, with a resolution increase from VGA (480×640) to WVGA (480×800). Their is a new interface feature called the “Single Contact View”, which consolidates your complete history of communication including (texts, calls, emails) for a contact into a single screen. Also has a new 5-megapixel autofocus camera. The autofocus camera's on these are okay, but they take way too long to focus. When taking a picture of someone you have to say wait for it, wait for it and then maybe it will take the picture before the people you are taking the picture of lose their interest.
The screen on the HTC Touch Pro2 has most of the same upgrades. Its screen goes up to a full 3.6 inches. From the looks of the picture the keyboard slides out and slants so that it makes it easier to use.
Battery life is apparently increased by 50% on the Diamond2 and “improved” on the Pro2. Any increase in battery life is good because my current battery life on the HTC Touch Pro Version 1 only lasts about a day because of all of the podcasts that I download directly to the phone.