raphael said:

Great, thanks for the links/information, Moth3r.

Someone has also pointed me toward:

'Star Wars Theatrical V3 DVD'

Posted by...........: Dark_Jedi

Any idea how this one differs from the others?

Check the summary at the link I posted; this is the version listed as GOUT V3 - dark_jedi.

GOUT is the acronym for "George's Original Unaltered Trilogy" - the official 2006 DVD release bonus discs that featured the theatrical versions.

Indeed, can anyone explain, in a nutshell, what the basic differences are between these various versions (to save trawling through many pages and potentially hundreds of posts!)

For example, the despecialised is 'not 100% authentic'- how does it differ?

Harmy's Despecialized Edition is not 100% authentic because it's a reconstruction of the theatrical version - many elements (title crawl, screen wipes, etc.) have been recreated (in HD). More explanation here.