Unfortunately, we don't have changelogs between these major updates, as they are considered "new products". CS-80 V4, for instance, has been rewritten from scratch, so pretty much everything changed. The main difference is the sound, V4 is much closer to the original hardware, and the GUI. For Prophet synths, it would be the same - sound excellence, but that's me oversimplifying it. I really wish I could give you a detailed changelog, but I hope this still helps.
