Here are the differences that were mentioned over at the Puggo thread. Most of them are from Trooperman who first noticed the discrepancies.
I just noticed another deviation- when Luke kicks Vader in the carbon-freezing chamber, he goes “Uhhh” instead of “Ahhh.”
Yoda makes a frightened “Ehhhhh!” sound just before Luke says “Like we’re being watched” and points his blaster at him.
“Oh, this is suicide! There’s nowhere to go.” present on the mono folddown.
Hmm… C3PO only says “Hello?” once when he thinks he hears an R2 unit AND the troop’s voice is different… AND the droid’s “Eh chuta” sounds like a different take
When R2 is being loaded into Luke’s X-Wing, C-3PO says the word “and” more audibly before saying "do take good care of yourself."present
C3PO has an ADDITIONAL LINE (not documented elsewhere) at the beginning of the carbon freezing scene. “Oh dear, what now? I don’t like the look of this.”
Yoda training scene
70mm mono fold-down:
-Right after the magic tree scene, 16mm features the classic TIE sound effects from “Star Wars”. The 35mm does not.
-Right after Luke puts the charge into the AT-AT and blows it up, the very next speeder Veers’ AT-AT shoots down has an airplane sound effect in the 35mm which is mixed much, much softer in the mono.
-Music is generally mixed much more prominently, with much punchier brass and violins, in this mono track. For a good example see the Hoth base scene right after the power generator is blown up. The music is inaudible in the 35mm and only fades in when 3PO appears- the missing music is not only audible, but very prominent in the mono
-For instance, in that very same scene, right before Leia falls down, she screams twice in the mono mix. No extra explosion before she falls.
-And as C3PO is climbing up the ramp, the most prominent sound in the mono mix is the flutes and the swooping strings. In the 35mm, it’s C3PO footsteps on the ramp, and the ramp sound effect- only to have to dial the music back up for the next scene (Vader).
-The shot after the Falcon escapes Hoth, the X-wing flyover is not nearly as prominent in the mono-music is
-The asteroid field sequence- all the sound effects are drastically muted and some are entirely missing in the mono mix. Focus is on the music.
-The scene right before the big Han/Leia kiss on the ship…much louder computer sound effects on the mono.
-Right after Leia screams seeing the Mynock out the window…audio of her footsteps on-set much more prominent.
-Yoda: “Consume you it will…as it did Obi-Wan’s apprentice.” For the mono mix, a different, less aggressive take of “as it did Obi-Wan’s apprentice” has been spliced in.
“How ya fealin’ kid…ya don’t look so bad to me”… Chewie’s noises are all missing.