*R2 does not have the ability to teleport behind rocks.
*Tatooine doesn't have magic rocks that appear out of thin air.
*Obi-Wan doesn't make noises like THAT.
*Greedo doesn't shoot first.
*Jabba doesn't send incompetent bounty hunters that miss at point blank range.
*Jabba doesn't send bounty hunters to kill Han, then let him off the hook.
*Jabba doesn't let Han step on him.
The Empire Strikes Back:
*The Emperor doesn't explain something to Vader they both already know.
*Vader doesn't act like a teenage girl coming home after curfew and feign ignorance lying to Palpatine's face.
*Vader doesn't calmly say "alert my star destroyer blah blah blah" when he's seething with rage.
Return of the Jedi:
*Jabba isn't the type to let bad fake looking CGI performers entertain him.
*Vader doesn't attempt standup comedy when he throws human batteries down into reactor shafts.
*Cities don't celebrate the destruction of their own military bases.
*Luke doesn't have visions of creepy pedophile looking teenagers he's never met before.
I might be missing some, but as you can see, the SE versions tamper with the original films in significant ways.