Not even close. H8 is a low-power, low-output halogen bulb used primarily in fog lamps. D2S is a high-output metal-halide discharge bulb used in headlamps. They are not physically, electrically, or optically compatible. You can find "HID kits" to put a rebased HID bulb in place of an H8, but they're dangerous and illegal; see here.
Thanks mate! So if I wish to replace my existing H8 halogen bulb to a HID one, will D2S fit?