It seems like HTC has run out of product names, as we can't help but to think that the HTC Touch Diamond2 and Touch Pro2 are poor product names considering the upgraded features both models have received.
Starting with the Touch Diamond2, it has been given a new 3.2-inch 480x800 resolution WVGA touch screen, which is a nice step up from the Diamond's 2.8in 640x480 VGA display. Other improvements include 512MB of ROM compared to 256MB and 288MB of RAM compared to 192MB. However, gone is the 4GB of internal storage of the Diamond and both models use the same 528MHz Qualcomm processor.
HTC has also added what they call a Zoom bar which is a touch sensitive area on the handset just below the screen that allows you to zoom in and out when you're using your web browser. The Diamond2 has also been given a 5Megapixel camera in favour of the older models 3.2Megapixel camera and HSUPA which was missing on the old model.
The bad news is that the Diamond2 has become 7.5g heavier and 2.35mm thicker, as well as 5.85mm taller and 2.1mm wider. The battery life seems to have been improved by 30min talk time in 3G mode and the standby time by an impressive 104h. You can find the product page here
The Touch Pro2 has been given a similar overhaul, although in this case HTC has taken inspiration from its older TyTN II in terms of design and the rounded edges and the flip-up screen is back. The screen measures 3.6-inches and has the same WVGA resolution as the Diamond2. Neither the memory or processor have been upgraded in comparison to the old Touch Pro.
New features include the same Zoom bar as the Diamond 2 and HSUPA. The weight is up 10g and the Touch Pro2 is 14mm taller and 8.2mm wider than the Touch Pro, although it's also 0.8mm thinner. Unlike the Diamond2, the Touch Pro2 has had its battery life decreased compared to the Touch Pro as it only manages 270 minutes talk time and 454h standby in 3G mode, compared to 378 minutes and 462h for the older Touch Pro. You can find the product page here
The Touch Diamond2
The Touch Pro2