So are the Master classes basically super buffed versions of the change classes?

No. The Master Classes Command- Sure, with their ability to Change, the Change Classes have some Control over their Aspect, but Master Classes are able to alter the very nature of their Aspect and channel it through themselves. Caliborn basically makes the entire Alpha Timeline of Homestuck to suit him, Reality is bending on its own to suit him because of his powers. Similarly, Callie can manifest physical circumstances through her Art, pacifying the Meenah-Vriska Fight and waking John up by merely drawing her Fanfiction. It’s another completely different level of control. Which… I guess you could consider it to be ‘super buffed versions’? If you wanna go that way.