They are the same bulbs, but running HIDs in a halogen housing is dangerous to other drivers and I would not recommend it. There are plenty of very bright Halogens you can use that won't blind oncoming traffic and actually function in fog where a HID is not going to.
2000 Mustang GT Steeda build #48. Bolt ons, suspension, Novi 2000.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.