OSRIC 2.0/2.2 versus 3.0: What's really changed?

Since the public release of OSRIC 3.0 in late 2025/early 2026, I've seen a great deal of interest online in the nitty-gritty details of what makes this new version substantially different from previous ones. Obviously, there's new art and a fresh layout and presentational style intended to make original AD&D easier to learn, teach, and reference than ever before. Beyond that, though, there was…