Color Temperature is a measurement in Degrees Kelvin that indicates the hue of a specific type of light source. Many people believe the misconception that color temperature is a rating of the brightness of the bulb or HID kit. This belief is completely false. The reality of the matter is that the higher the color temperature, the less useable light output you will obtain. However, it is also a fact that, all HID light is brighter than Halogen, even if it is a 12000 Kelvin, the Lumen still maintain well over 2500lm; which is still 2x brighter than 55W Halogen.
Even though some halogen bulbs are coated with blue to get that temperature color you are looking for (ex:6000k), there's a big downside to that. The blue glass actually robs lumens and the bulb's performance is affected. So you end up having a bulb that reaches the promised color but gives you even less road coverage than your standard clear halogen bulb. If you want the white/blue colors and great performance, only HID will be able to give you both.
