You have no idea, because you have a preconception. "Fan cuts pffft."
Prometheus Special Edition the "Agent 9" fan cut, has colour corrected shots, finished effects. In the prior post, the link has a full list of changes, I am just glad Pietro Scalia does not cut for Fede Alvarez.
4K77's a "fan cut" that essentially, it's a print of the original Star Wars painstakingly restored by fans. 4K80's still being worked on as it is in pretty rough shape, 4K83's in good shape.