Lets see from memory of having both devices...

HD2 specs vs N900 specs

* Thinnest device for its screen size to date vs fattest phone created in last three years, qwerty or otherwise (well I haven't checked but I am probably right)
* Compass vs no compass
* 576 Mb Ram vs 256 MB Ram
* Steel/Carbon fibre construction vs some kind of plastic
* 1ghz CPU overclockable to 1.3GHZ vs 600Mhz overclockable to 1.1 Ghz (well some devices anyway)
* Capacitative mutitouch vs resistive screen (don't add your prehistoric views when every phone is headed this way, I bet you were the same with touchscreens)
*USB host vs no USB host
*157 grams vs 181 grams
* Scratch resistant screen vs easy scratch screen
* Sturdy USB port build vs Falling out USB port issue
* 4.3" screen vs 3.5" screen (and its meant to be a tablet)
Memory is micro SD upgradeable but one area its beaten