I don't think there is a difference. Also, I have never seen the four piece cork sump gasket on any of the pre 86 cars I've worked with. The rubber gasket seals quite well the straight pieces, but where the half circles are, the gasket usually is not compressed at all. So my advise would be to use the rubber gasket, but use plenty of additional silicon sealant around the half circles. These are also the lowest points and therefore likely to leak.