Leucism is just a form of reduced pigment. A pied animal is actually leucistic.
YB Ivorys and all the lesser/butter/mojo/fires etc 'supers' are infact leucistic. Ball breeders name the different visual leucistic traits with 'fancy' names to indentify which animals they were produced from or make them sellable.
Try a google I'm sure wikipedia etc has more indepth info if you need it.![]()