It's rather difficult to photograph a television screen, but here's a blurry pic of the lower case "rebel" from my pre-ANH bootleg.

http://home.austin.rr.com/obiwanspicoli/rebel.JPG

Originally posted by: ChainsawAsh
- Aunt Beru has a different, younger-sounding person dubbing for Shelagh Fraser, whose real voice has never been heard in a Star Wars film to date
I've always thought the same person did the voice-over for both sound mixes. It sounds like the same person to me. I'd like to hear other opinions. Here is a wav comparison with the mono voice followed by the normal voice.
Originally posted by: ChainsawAsh
- The voice of the stormtrooper searching for the droids on Tatooine is different

To be more specific, there's a different line as well. The Stormtrooper who knocks on the door which R2 and 3PO are hiding behind says, "Alright, check that side of the street. It's secure. Move on to the next one." Instead of, "Alright, check this side of the street. The door's locked. Move on to the next one."

Regarding the 70mm version of TESB, in addition to the visual differences that Neil has mentioned, there are numerous audio differences as well. These differences can be heard in the Special Edition and the 2004 DVD, and many can also be heard on the original 1980 "Story of" album. The audio differences include (but are probably not limited to) the following:

-On Hoth, right after C-3PO tells R2 to "Switch off," R2 gives out a little 'blurp.'

-When Luke finally collapses in the snow, he lets out a grunt as he lands on his face. (Also in the 1980 "Story of" album)

-Han says "until I can get the shelter up" instead of "until I can get the shelter built." (Also in the 1980 "Story of" album)

-Luke says an additional "Ben... Dagobah..." just before Han says "and I thought they smelled bad on the outside." (Also in the 1980 "Story of" album)

-When C-3P0 tells Luke "It's so good to see you fully functional again," Luke replies "Thanks, Threepio." (Also in the 1980 "Story of" album)

-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.

-When R2 is being loaded into Luke's X-Wing, C-3PO says the word "and" before saying "do take good care of yourself."

-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!"

-In the asteroid field, after C-3PO says "Oh, this is suicide." He says, "There's no where to go."

-Luke says "You're lucky to get out of there" instead of "You're lucky you don't taste very good." (Also in the 1980 "Story of" album)

-Yoda makes a frightened "Ehhhhh!" sound just before Luke says "Like we're being watched" and points his blaster at him. (Also in the 1980 "Story of" album)

-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.

-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?"

-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.

-During the duel, when Luke knocks Vader off of the platform, Vader lets out an "ooooh!" instead of an "aaargh!"

-Lando's line at the end, "Luke, we're ready for takeoff." is a different take. (Also in the 1980 "Story of" album)

That's all I can remember right now. There's likely to be more that I'm forgetting about or am not aware of.

The 70mm version of ROTJ has far less differences. The only one I can think of right now is Han saying, "It's alright, I can see a lot better" instead of "It's alright, trust me." This line is also in the original 1983 "Story of" album.

Scott