I heard that Richard Lester was told to re-film as much scenes as possible of which were already filmed by Donner so he (Lester) could receive a directors credit on the film, from what I've read in numerous articles dating back to the 90's the theatrical cut of Superman II has only about 30% of Donner footage which all include Gene Hackman because he (Hackman) didn't come back to film when Lester came onboard.
Aye, I read this too, and they used a body double for some scenes that were re-shot with Luthor, presumably with his face out of shot. I think they may even have used a sound-a-like to overdub some lines as well, not sure if I'm mis-remembering that part though.
I do think that they just chose to use some deleted scenes just to fill the 'donner' cut up with as much unseen material as possible, like that example mikey1974 was talking about, same with the 'Don't you believe in freedom of the press?' line, I mean, who on Earth would think that was a better line than would you care to step outside, even apart from the line just being better because it is more direct and to the point about it being 'ok you three, it's fight time', it's a good hark back to the diner scene.
I was just watching the 'superhero rewind' reviews on youtube, of both the Lester and Donner cuts, and it was one of the few times I just about completely disagreed with the guy. He felt the Donner cut was better, but at the same time, he said that Donner had rushed through all the Brando scenes, and had wanted to re-shoot them.
This makes a lot of sense to me now, as I never really liked the Brando scenes in the Donner cut, despite thoroughly enjoying his turn in SMTM.
I think he looks a bit silly now and again, the floating head, and like an old man in his pyjamas, and is overused to the point of losing his mystique.
I prefer Superman getting his powers back offscreen to the bit with Jor-El giving Clark that big flashing shoulder clasping bit.
I also think all the scenes with the villans, Luthor and the Daily Planet staff plays much better in the Lester cut.
and I miss the Paris rescue and Lois' jump into Niagra Falls...
eh, I have went on about the differences before, and at length, some I am forgetting as well, but even though it has some cheesey humour added, I prefer watching the Lester cut, and I think I might even have preffered it this way, if Donner had shot it the way he wanted in the first place.
Because I don't like how the Lois/Clark secret I.d. ideas played out in the Donner cut, it's pretty much perfect for me the way it plays out in the Lester cut, and that is a huge part of my enjoyment of watching the film.
Ideally, as what happens with these alternate cuts, I'd want to do my own edit, I do prefer seeing the battle at the end without the really daft bits.
But man, the cut of the final battle on the released 'Donner' cut, it's pretty bad the way it plays, again, it's like they just wanted to make it as different as they could from the Lester cut with what was vailable, when what was already in the film *was* the best availiable material. I mean, Donner didn't shoot any scenes of the final battle.
) brings Superman into the story earlier and we get to see him in action. 
