Hi Helicopterray, i think that it is exactly a difference of rules between one country and another. I know in NZ and Oz that people just go by pn for aircraft that are built by OEM or under licence. We have people operating all sorts of licence built aircraft, 206's, 300's, 500's etc, and all just use whichever parts they can get hold of.
I believe that in the UK the CAA has said that it is an Agusta 206, therefore parts have to come from Agusta, even tho the parts are actually manufactured for Bell.... just bureaucratic bollocks trying to make aviation more expensive, but not increasing safety!