DVD is the Ultimate Edition which has a new encode vs the Special Edition but still from the same source.
The UK Blu-ray reuses the VC-1 encode of the StudioCanal HD DVD released in a few countries, but doesn't suffer from the pitch problem that one had. MP3 comparison of USA vs UK audio
(full specs for each release here)
Blu-ray - USA - Lionsgate - Region ABC - 21.64Mbps AVC - DTS-HD Hi-Res 5.1 3018Kbps (48kHz/24-bit)
Blu-ray - UK - Optimum - Region AB - 17.05Mbps VC-1 - DTS-HD Master 5.1 1834Kbps (48kHz/16-bit)
HD Promo - "Rambo Ultimate Edition" DVD promo (from Lionsgate "Rambo" BD) - 17.15Mbps MPEG-2 (23.976p)
First Blood - DVD vs Blu-ray (USA) vs Blu-ray (UK) vs HD Promo Screenshot Comparison
Colors and framing are identical between all four sources (including a black bar down the left side), except that the DVD has a vertical stretch and the UK has a tiny black bar added on the right that covers some pic info. Clearly all come from the same source master.
Here's the breakdown as I see it:
Promo = master + MPEG-2 compression
DVD = master + vertical stretch + downconversion + MPEG-2 compression
USA BD = master + DNR + digital scratch removal + minor EE + AVC compression
UK BD = master + tiny black bar + VC-1 compression
EDIT: Really, though, this film is in dire need of a remaster. The current one has a strange video-like structure to the noise instead of film-like grain.
I noticed many instances of motion trailing (ghosting) when I first watched the USA disc, particularly the scene around the 6-minute mark on every shot of Sheriff Teasle's face. I figured this was all down to the DNR, but the UK disc appears to have a certain level of trailing too. It even appears on the DVD, but considering all the compression artifacts at close viewing it's tough to say.
Video sample of trailing - USA vs UK Blu-rays (18.3MB, 720x638 YV12 encoded with Lagarith lossless video codec)
This is a direct crop from the same section of each 1920x1080 video. Play it at 100% and you'll get an exact reproduction of a part of the video played on your display.
The USA/UK/Promo comparison pics show off the DNR and scratch removal artifacts most thoroughly.
Random: I've finally figured out why I prefer the UK cases. They feel sturdier, meanwhile they're actually lighter.