What's the big difference between adjusting photos with RAW and adjusting photos after JPG? (with PS)

PHOTOSHOP above CS3 supports RAW format, which is the original record of lens exposure when you take a photo. You can adjust the ISO (exposure), white balance, curve and so on of the photo without any changes to achieve the best results. JPG format has been processed and compressed by the camera's CPU at the time of publication, so the above parameters cannot be adjusted. I always shoot in RAW format, that's why.