I remember reading that the actual Jympson assembly didn’t have the scenes aboard the Tantive IV at all because they hadn’t been shot yet, and that was yet another contributing factor to that version being so poorly received.

The way I see it, this probably describes the post-production assemblies as best as can be currently understood.

Version 1.0 - John Jympson’s assembly
This is probably the version that is most referred to as “the Lost Cut” and where the famous assembly of the Cantina scene and the other surviving black and white snippets have come from. Probably nothing more than colored liter paper for special effects inserts, most likely rendered the final battle a complete mess.

Version 1.3 - Initial revised edit
This is the version shown to Lucas’ friends (De Palma, Spielberg, Coppola) with many changes from the initial Jympson assembly, mostly due to this being a version intended for some sort of public screening. This may or may not have had the Anchorhead scenes included; conflicting sources say this was excised after Jympson’s initial edit while others suggest that it was in the version Lucas’ associates watched (the existence of the color edit of the Anchorhead scenes would suggest this). This cut likely had better pacing than the Jympson cut, was composed entirely of on-set audio with film scratches for laser fire and featured the World War II dogfight footage during the space battle sequences.

Version 1.5? - Workprint
This version, if my hypothesis is correct, was the version screened for the 20th Century Fox executives (as described in Empire of Dreams). By this point the Anchorhead scenes were definitely gone, as were likely other scenes (Chief Bast and Vader), and special effects were likely beginning to seep their way into the cut as well as some post production audio (very rough and temporary). Chew and Hirsch’s reorderings were almost certainly taking root by this point as well, and this may have been temp-tracked with the Stravinksy and Holst music. It was a far more complete film by this point and easy to see why it may have given some of the shareholders hope.

Version 1.7 - Scoring Workprint
This would be the version that John Williams wrote and performed the score to, and if my guess is correct, would have been mostly complete. Its existence is supported by the existence of color screenshots of many scenes in the Insider article (which are described in the official Carol Titelman script) and pictures taken of Williams at the podium, as well as sections of the complete soundtrack. I can with a degree of confidence conjecture the contents of this version (against the theatrical cut):

Aunt Beru filling the glasses of milk (actually described in the screenplay as a brief segue scene)
The original rear-projected Landspeeder scene (and an effects shot of the speeder’s scanner; supported by the original score and the Art of Star Wars). This was likely fully ADR-ed and later the dialogue was applied to an uncut effects shot intended for the start of the scene.
The original exterior shot of Ben Kenobi’s home.
Luke deciding against re-applying Threepio’s restraining bolt.
A very slightly extended entry into Mos Eisley? Either that or a substituted shot in the final edit.
Han and Jenny in the Cantina.
The Cantina snitch’s full journey outside may have been in this cut.
An establishing shot for the scene where Tarkin directs the Death Star to Alderaan; this shot is described in both the original screenplay and the novelization and can be seen in the original Insider article.
As Ronster has noticed (and may actually be correct about for once), the escape from Tatooine may have been reordered for logistical consistency; supported by the laser fire sounds matching up better with reordered shots and a couple of music jumps.
The coda to Alderaan’s destruction. This is a stretch, but there is a high quality color image of Leia being led away (that appears to be a screenshot). If true, the entire scene in the Falcon’s hold may have originally been unscored. Additionally, Alderaan’s explosion undergoes a noticeable jump cut in the final edit, which may suggest the shot was altered at the last minute.
The shot of the Falcon escaping (repurposed for the final battle) may have already been reshuffled considering the music in both scenes lines up from the original soundtrack.
Han and Luke congratulating each other after the dogfight scene (the dialogue is described in Ann Skinner’s continuity script). This may have been cut in the end due to an awkward ad-lib from Harrison Ford transitioning into the next scene.
A couple of extra shots of the briefing room and in the hangar (I have a conspiracy theory about the Biggs hangar scene but it’s best left out of this).
Many effects shots (all over the film but especially during the final battle) were likely temporary composites or earlier versions. One screenshot from this version shows Yavin as having been removed from the composite of a shot during the final editing sessions, and likely other shots were different or rougher as well.

As best as I understand it, this might describe the various versions rather well.