In the OT the actors would regularly be like "I don't think this line sounds good let's with this instead"
But in the PT everyone just went along with everything due to lack of experience and not wanting to be hard to work with/think they're better than the director
That's just about the opposite of the relative experience of the actors involved in both trilogies.
The original trilogy was filled with almost completely inexperienced actors. The prequels were mostly cast with experienced performers, excepting the child actors of course.
The real difference is that Lucas didn't actually direct most of the original trilogy in the first place.
I think Mark Hamill has mentioned before that there were times when Harrison Ford pushed back against Lucas that Han Solo would never say the lines he was given, and got them changed as a result.