Originally Posted by golfdude
What's the difference between a xenon light and a High intensity discharge headlight? In the magazines both words are used interchangably to describe the bluish-purple lights on high end vehicles such as BMW's and Mercedes. Is it the color that is different? And when looking for lights, I see different symbols, such as H7, H1, what's the difference and which one should I get.
Xenon is a gas. HID is a method of getting the gas to illuminate. I >think< HID bulbs have Xenon gas in them, but plain Xenon bulbs without HID ballasts just have a normal incandescent filament. HID will be muc higher intensity light, much closer to daylight look. Regular Xenon bulbs are a way to achieve a HID look without paying the money, and depending on the application might be good enough for you. Go browse some of the manufacturer web sites (Phillips, Sylvania, etc.) and read up.
H1, H7, etc. are sizes/shapes of bulbs. Crossfire headlights (high and low) are H7.