I'm trying to get done with some old blog posts that were started but never finished. So here's one:
Here we have some interesting commentary from StarWars.com regarding differences between the original films and the DVD Special Editions. We don't know who the author is, but the page presents itself as the "ultimate authority".
I highly recommend scanning through the article, but I'm also providing links to the original images. The following highlights are regarding some debated material, including the Death Star and some images relating to the scaling of the Falcon.
N.B. This 'backstage info' is interesting, but not canon.
49 of 122
The original shot of Alderaan also had effects artifacts in it, appearing as a hazy blue outline that surrounds the planet.
50 of 122
The original laser blast was hand-animated to have jagged lightning-like fingers of energy surround Alderaan, which didn't scale convincingly. The Special Edition instead had the atmosphere ignite as it spread from the impact point.
51 of 122
The original jump-cut explosion was replaced with a blast that featured a shockwave ring and more properly scaled debris.
54 of 122
In 1997, the original matte painting of the Falcon was replaced with one that used a digital ship model as a foundation. Also, the Death Star hangar design was changed to match the one seen in Return of the Jedi.