Blu-ray vs. 4K UHD Blu-ray screenshot comparisons are coming later for MS. 45 via @TimesSqKungFu. Here's one really impressive side-by-side zoomed comparison between the 2014 Blu-ray & 2025 4K UHD Blu-ray from @ArrowFilmsVideo.
SOURCES: Blu-ray (left), 4K UHD Blu-ray (right).
The framing isn't perfect, as I did this in Windows, zooming in on each. I think Frankie showed this shot before, and it was the full shot. This zoom-in shows how much more impressive and realistic the 4K with HDR (tone-mapped here in SDR) looks. The color timing also had a drastically beautiful change. Full set in just a bit.