Originally Posted by Jonathon
The Nexus S line is ever expanding, with at least 4 different variants out there now. Most of you may already know the differences, but others may not. This is designed to help you understand the differences and avoid damaging your phone by using something not designed for it.
Variants (in rough order of release)
Nexus S from T-Mobile and Europe early on - i9020T
Nexus S from Vodafone and most of European countries - i9023
Nexus S from AT&T and Canada - i9020A
Nexus S 4G from Sprint - SPH-D720
The i9020 series (A and T models) as well as the D720 (4G) all feature SuperAMOLED displays, while the i9023 features a SuperLCD (SLCD) display
The i9020T and i9023 both support UTMS 900, 1700 and 2100mhz
The i9020A supports UTMS 850, 1900 and 2100mhz
The D720 (4G) supports Sprint's CDMA and WiMax networks, and doesn't use a SIM card
Things to be aware of
Nexus S (GSM) and Nexus S 4G ROMs are different. DO NOT flash a GSM ROM onto your 4G or vice versa, it will not end well.
Most kernels support all different models with the same kernel, but check to make sure first. Some may be 4G specific, whilst others like Netarchy support all variants.
Radios are designed for specific phones from specific areas and regions. Unlike the Galaxy S there are not kajillions to choose from, with some being seen as 'the better one'. Try using the one your phone came with originally, particularly if you bought locally (or through your carrier). If you imported, try using a radio which will match your local conditions/carriers. Once again, 4G and GSM radios are NOT compatible, do not mix them around.
I hope this info helps someone, feel free to mention something I may have missed. It is particularly important here at RootzWiki to know if a ROM is 4G compatible or not, as there is no dedicated 4G section.