BIG difference in the entire unit !
The xenon setup has brilliant White angel eyes that are used as daytime driving lights ( light setting in the OFF position ).
You don't get this with the halogens. When the lights are in the OFF position, you don't get ANY daytime driving lights. The only way you can light up the angel eyes ( which are half brightness on halogen setup ) is to turn the sidelights on or the auto lights, but I assure you, the halogen angel eyes are rubbish until it is nearly night time !!
I wasn't made aware of this in any showroom i visited before buying the car and to be honest, I'm not very happy about it. You don't see Audi's driving around with half the brighness LED's on the front, it's their trademark, and the angel eyes are supposed to be BMW's trademark.
Big mistake from BMW.
Apart from the lights though, I absolutely love the car from top to toe. It's far better than the E92 that I have just got rid of. ( which had xenon angel eyes !!! )