Ok.... So it's been beaten to death that the euro spec 2011's get the LED angel eyes like the new 5, 5 GT etc.

My question is, what is TECHNICALLY different between the two headlight assemblies - Euro & US spec? What is different with the angel eye technology on the 2011's? Obviously they are LED, but what else is different?

Has anyone been able to do a side-by-side with a US spec X5 and a 2011 5 series to see if there is any interchangeability?