The ORIGINAL theatrical versions were NEVER released on DVD.

The 2006 DVDs don't include the theatrical versions, but the 1993 laserdisc versions. They have a new audio mix (from 1993), different color timing, different editing (missing frames) ... The SW DVD is actually a merge of the 1993 laserdisc version with a 1977 theatrical opening crawl.

Star Wars had more official releases.

The most notable was the 1981 theatrical re-release, when they renamed the movie from "Star Wars" to "Star Wars Episode IV : A New Hope", created a brand new crawl, reworked the opening sequence ...

The 1985 home video release had a new sound mix, and there was also this 1993 laserdisc which had many small changes (both video and audio) which ended up being a source for the official "GOUT".

There are also many fullscreen "pan and scan" versions and every one has a different "frame composition"