the bit that bolts to the wheel is the same
the bits that bolt the brakes up to are different for drum (no lug for the brake caliper) to normal to cossie (lug for brake caliper mount 10mm further out)
if you are using a drum rear end and want to convert to disc then it is far easier to use the whole rear end

there is a way to swap shafts over but it's been about 2 years since i did anything like that and i dn't have any pics of what to do either

there is a user called taps on this link