OK, so I've recombined the two lists of differences here and put them in order of the movie. I also pulled out the video differences, left the unconfirmed ones in italics and seperated the categories of audio differences.

The Empire Strikes Back
The 70mm version of the film was substantially different from the 35mm version that was more widely seen.

VIDEO:

• After the Probot lands and moves left, there is an optical wipe to the overhead shot of Luke on his Tauntaun.
• After Luke wanders through the snow and falls face down, there is an optical wipe to Han instead of a straight cut.
• The bacta tank scene starts on a close-up of Two-One-Bee and pans right to a close-up of Luke in the tank. It then cuts to FX-7 extending its arm to the tank. There is no cut to Leia, Han and Threepio observing. (Possible that this could be re-created with the full-screen version)
• In the snow battle scene, when Luke drops into the snow after throwing a charge into the Imperial walker, the AT-ST in the background has no atmospheric depth. It looks too close and small.
• The Emperor does not fade in at the start of his communiqué with Vader.*
• Millennium Falcon sensor dish is not visible with Luke on weather vane. The position of the vane is also different on the background.*
• The telepathy between Luke and Vader during the "Hyperspace" cue has straight cuts instead of quick dissolves.
• The frigate footage at the end looks decidedly different.*

AUDIO MIX DIFFERENCES:
NB, these are items that are present in the 35mm mix, but are greatly dialed down under sound effects or the score.

• On Hoth, right after C-3PO tells R2 to "Switch off," R2 gives out a little 'blurp.' More pronounced on the 70mm.
• When Luke finally collapses in the snow, he lets out a grunt as he lands on his face.
• The first time Rogue 2 says, "Commander Skywalker, do you copy?" is placed after he says "Captain Solo, do you copy?" instead of being placed before. The second "Commander Skywalker, do you copy?" is not on the Super 8 reel. It may have been edited that way for the Super 8, but I found it odd.*
• Rebel dialogue immediately following the line "The first transport is away!" is easier to hear. This includes “...let’s go, move, move!”
• When R2 is being loaded into Luke's X-Wing, C-3PO says the word "and" before saying "do take good care of yourself." The 2004 DVD really cranks up the quiet “and”.
• More rebels calls of 'retreat' when Walkers attack.*
• In the asteroid field, after C-3PO says "Oh, this is suicide." He says, "There's no where to go."*****
• Yoda says the word "Run!" before "Yes. A Jedi's strength flows from the force." The following lines "But beware the dark side. Anger, fear, aggression. The dark side of the force are they. Easily they flow, quick to join you in a fight" are also much louder and clearer.
• While C-3PO is on Chewie's back when they enter the carbon freezing chamber, the line "Now remember, Chewbacca, you have a responsibility to me, so don't do anything foolish" is louder and heard more clearly.
• More crowd noise as people flee Cloud City.*

ALTERNATE AUDIO:

• Luke: "Echo Three to Echo Seven. Han 'ole buddy, do you read me?" -Different take. *, **
• Luke - "I don't pick up any life readings" - Different take *, **
• Han - "I'm coming back" - Different take instead of the more widely heard “I’m going back” *, **
• Han says "until I can get the shelter up" instead of "until I can get the shelter built."
• Luke says an additional "Ben... Dagobah..." just before Han says "and I thought they smelled bad on the outside." In the 35mm, apparently, we only hear Luke mumble when we can see his mouth.
• Rogue 2: "Captain Solo, do you copy?" -Different take *
• When C-3PO tells Luke "It's so good to see you fully functional again," Luke replies "Thanks, Threepio."
• The line "Headquarters personnel report to Command Center" is repeated three times instead of two. *
• The line "The first transport is away!" is said in a different voice altogether. *
• Luke now says "This is it" just before his wingman (and soon, himself) is hit by AT-AT fire. His lips move, too, but I never noticed before.
• Han's line "Transport, this is Solo. Better take off, I can't get to you. I'll get her out on the Falcon" is followed by, "Come on!"
• Leia: "They're getting closer." -Different take *
• Han: "Oh, yeah? Watch this." -Different take *
• Luke says "You're lucky to get out of there" instead of "You're lucky you don't taste very good."
• Yoda makes a frightened "Ehhhhh!" sound just before Luke says "Like we're being watched" and points his blaster at him.
• The Imperial fleet establishing shot after the magic tree scene has a different TIE fighter sound effect.
• Obi-Wan’s lines are not as ‘echoed’.*
• Cloud City Patrol - "Any aggressive move will not be tolerated!"* This replaces “You will not deviate from your present course” ***, *****
• Cloud City Patrol - "Permission granted to land on platform 3-2-7. Any deviation from..." - Han cuts of comlink.
• Lando tells Han, “Yeah, I'm responsible these days. It's the price of success.” The 8mm continues “And you know what, Han, you were right all along. It's over-rated.” as C-3PO talks with the other protocol droid.*
• In Cloud City, after C-3PO says "That sounds like an R2 unit in there. I wonder if it..." he says "Hello?" only once instead of twice.
• Before C-3PO gets shot, a different voice says "Who are you?"
• During the duel, when Luke knocks Vader off of the platform, Vader lets out an "ooooh!" instead of an "aaargh!"
• C-3P0 adds a very sarcastic “Oh my, so nice to be together again” before he says “I thought that hairy beast would be the end of me.” *
• Leia "I know where Luke is" ***, ***** is replaced by "we have to go back".*
• Leia says the line "Lando, hurry up, we've got company!"* as Lando is rescuing Luke from the weathervane. This line replaces Lando’s line of “OK, let’s go”. ***, ****, *****
• C-3P0 "Get away from there,” prefaces “You don't know how to fix the hyperdrive! Chewbacca can do it!”*
• Lando's line at the end, "Luke, we're ready for takeoff." is a different take.
• In the final scene, there is no tracked music from "Yoda and the Force".

* 8mm
** The Story of TESB LP
*** TESB GOUT DVD
**** TESB:SE 1997 LD
***** TESB:SE 2004 DVD