Either version of SpyderX will include the same, newly-developed hardware.
There are a number of software differences. The most important includes the Expert Console, which lets you take control, and drive the software any way you chose, and the nearly infinite number of standards you can calibrate to with it. The ability to calibrate projectors is another feature often mentioned as the one that people upgraded for. StudioMatch, for easy control of a group of systems to the same values, is also important for those using multiple computers. The remaining additional features are mostly in the area of advanced testing and reporting.
Please consider these advantages carefully before purchase, as there is no upgrade path from SpyderX Pro to SpyderX Elite.