Actually, XE is B7333. Where as the previous versions of OneWorld were B732, B7331, B7332, etc... The difference between those are much like KB555 said. They were releases of OneWorld that had slightly improved performance.
ERP8 and JDE5 are basically the same thing. Both of them are a collection of different modules that are grouped together when the product is sold. They both are essentially OneWorld Xe with a service pack and update baseline.