Though some sources claim that the HTC EVO 4G is nothing else but a modified version of the HTC HD2, a lot of differences are there, moreover, very substantial, and the thing is not only that the first model is the Android Phone, and the second runs on Windows Mobile.
First of all, it is worth noting that the EVO 4G is 2 mm wider and thicker, but 1 mm shorter than the HD2. In addition, the Android Phone is 13 grams heavier than its cousin. Although both models are built on Qualcomm Snapdragon platform with 1 GHz processor, EVO 4G uses a newer processor QSD8650, but not QSD8250, as in the case with the HD2. It is also worth mentioning that EVO 4G has 512 MB of RAM, while HD2 has 567 MB.
Among other structural differences are the presence of 8 megapixel camera on the EVO 4G (HD2 has only a 5 megapixel camera). On the other hand, the latest model allows you to download data from the web on the actual speed of 10 Mb/s, and HD2 only theoretically supports this speed in 3G networks.