The 320EX is the more powerful of the pair, offering a guide number of 32 and a new video light option, which offers continuous light for video shooting. More importantly for non-video shooters is the expanded suite of wireless capabilities, including the ability to work in channels and groups for increased tweakability when working with more than one flash. Because it's being release in conjunction with the T3 and T3i, it also has very tight integration with their wireless flash control systems. The head can zoom and swivel as well for bouncing or other flash effects. It brings a price tag of $249 starting in April.