This might sound stupid but what is the difference between Bi-Xenon and Xenon headlights? I see some cars have bi-xenon and some just get xenon. I did a search and found nothing.

 

Bi-xenon means one buld for both high and low beams:

With bi-xenon there is a shield activated by a solanoid integrated into the bulb that will move up and down when you turn your brights on. Shield down blocks light that shines up, thus you get low beams. Shield up removes the shield and shines everywhere, thus brights.

So basically you have high and low beams coming out of the same projector.

Hope that makes sense....