Display:
HTC Diamond2 : TFT Resistive touchscreen, 65k colors, 480 x 800, 3.2″ HD-Widescreen, 32bit db
HTC HERO : TFT Capacitive touchscreen, 65k colors, 320 x 480, 3.2" ,24bit db
NOTE: HTC TD2 has Higher Resolution, Wider & Better Colors Screen.

Dimensions:
HTC Diamond2 : 107.9 x 53.1 x 13.7 mm & Weight 117.5 g
HTC HERO : 112 x 56.2 x 14.4 mm & Weight 135 g
NOTE: HTC HERO is Bigger & Heavier than the HTC Diamond 2.

Memory:
HTC Diamond2 : MicroSD up to 32GB + 300mb user intrnal memory = 32.3 GB
HTC HERO : MicroSD up to 32GB + 300mb user intrnal memory = 32.3 GB

Camera:
HTC Diamond2 : 5MP, Touch focus, Video {(640×480)VGA in (850Kbps)@15fps} High-resolution
HTC HERO : 5MP, Touch focus, Video {VGA 15fps}

3G:
HTC Diamond2 : 7.2Mbps HSDPA & 2Mbps HSUPA
HTC HERO : 7.2Mbps HSDPA & 2Mbps HSUPA

Talk Time:
HTC Diamond2 : 6 hours
HTC HERO : 7 hours

Bluetooth:
HTC Diamond2 : v2.0 with A2DP & EDR
HTC HERO : v2.0 with A2DP

OS:
HTC Diamond2 : Microsoft Windows Mobile ® 6.1 Professional Can Be Upgraded to Windows Mobile ® 6.5
HTC HERO : Android OS, v1.5

Wi-Fi:
HTC Diamond2 : Wi-Fi 802.11 a,b/g
HTC HERO : Wi-Fi 802.11 a,b/g

CPU:
HTC Diamond2 : Ram 288, Rom 512, Single-Core Qualcomm MSM7200A 528 MHz, 64 MB Dedicated Graphics Chip
HTC HERO : Ram 288, Rom 512, Single-Core Qualcomm MSM7200A 528 MHz.

Battery:
HTC Diamond2 : Li-Ion 1100 mAh (HTC)
HTC HERO : Li-Ion 1350 mAh (HTC)

Colors:
HTC Diamond2 : Metallic Black
HTC HERO : Brown & White

Price:
HTC Diamond2 : 450 EURO
HTC HERO : 400~450 EURO

Design:

HTC Touch Diamond2

|____________HTC Diamond2________HTC HERO__________|

First YES/NO is HTC Touch Diamond, Second YES/NO is HTC HERO

USB-charge-----YES----------YES

USB Type------YES,mini-------YES,mini

Card slot-------MicroSD---------MicroSD

Flash Lite------Support Flash----Support Flash

DVB-H TV receiver-- NO----------NO

GPS----------YES----------YES

3.5 mm audio jack---NO----------YES

secondary cam---YES,VGA---------NO

Video Calls-----YES-----------NO

Touch screen----YES----------YES

Digital compass---YES----------YES

Java MIDP-----YES,v2.0--------NO

FM transmitter----NO-----------NO

FM stereo-----YES+RDQ---------NO

Office suite-----YES-----------NO

Accelerometer----YES----------YES

Full QWERTY-----NO-----------NO

Handwriting-----YES----------YES

Stereo Speakers--- YES-----------YES

3D surround Audio--YES----------YES

Integrated Audio chip-YES---------YES

Proximity sensor---YES----------YES

TV out---------YES---------YES

Slide type-----Candy bar----Candy bar

Navi-wheel-------NO----------NO

WMV9 player------YES----------YES

Flash video on web--YES----------NO

3D Image Engine---YES----------YES

3D Hardware Acc---YES----------NO

Graphic Chip-----YES----------NO

UI Type------TouchFLO 3D^TM----Android UI

Removable Battery--YES---------NO

Multi-touch input---NO----------YES

Scratch-Resistant--YES---------YES

Track Ball------NO----------NO

Via HTC Touch Diamond2 Forum