Definitely Nexus. It has Android.

I think between these two it really comes down to the the fact that if you like a droid system or Winmob. But than again the 4.3 inch screen on the HD2 is pretty amazing

There are many differences, but in the end it comes down to preferences and needs.

One is an Android phone, the other is a Windows Mobile phone; one has a 3.7 inch screen, the other has a 4.3 inch screen; one has a trackball, the other doesn't. They both have the processor and memory. I loathe Windows Mobile, though. I currently use a Motorola Droid, so I am bit biased toward Android, but your preferences/needs might differ from mine. I think Android has a brighter forward than Windows Mobile, but that's just an opinion.

I think that Nexus One is much cooler than HD2. Nexus One has cooler features than the HTC HD2. A great difference between these phones is that Nexus one has an OS Android 2.1 while HD2 has Windows Mobile 6.5.

I was browsing the internet and I have found these phones. I was wondering what could be the best feature of the phones. I was wondering which phone is cooler too. Can you guys distinguish their differences?