I believe that’s the case, yeah: If you buy the individual 4K releases, you get the new blu-ray pressing as a pack-in w/ the new 4K disc. But since the individual blu-ray-only releases came out BEFORE the 4K releases (before they were even announced, I think?) those discs are just repackaged 2011 blu-rays.
The covers, aside from the top banner saying whether it’s a 4K UHD or blu-ray only release, are identical otherwise.