As I understand it 4K UHD Blu-Ray discs are the same physical format as ordinary Blu-Ray discs. So any USB-connected Blu-Ray drive should be enough to read the files that make up the movie content if it can keep up with the higher data-rate. I suspect that most drives meant for computer use should be able to keep up since they are going to be faster than “1x”. For example the models sold by OWC advertises 6x and 16x speeds.
You may want to start with the open source VLC software. It may require some tweaking to get everything working well, but as free software, you may want to start with it before considering commercial software packages that may cost as much as a physical 4K Blu-Ray player.
I have a 4K TV and the new 2022 MBP with the M2 chip is also rated a 4k display. My thinking is that I am already spending $$$ for the Blu-ray Discs so I should therefore buy the best video definition of the discs I want so that in 5 years, I do not have to buy them again. I have no idea if my eyes can tell the difference, but I bet the kids’ eyes can………
You should be happy with VLC. It has a lot of options that you can tinker with. But it also tends to work well if you don’t want to bother with details. It’s free and sees good support also on macOS. It’s been around since forever.
In terms of drive, you can get fancy and spend $150 for a hefty box. But all you really need is a simple player with HDR/UHD support, a USB-C plug, and good reviews. This $70 drive fits that description.
I may be wrong: The newer version of that drive says that. The older version does not say that. Seems to be something fishy. Older version from 2018 van support a format that really did not exist until the early 2020s and the newer one does not support? Alarm bells are ringing………
There are several differences between Blu-Ray 1080p discs and Blu-Ray 4K aka UHD discs.
A ‘standard’ Blu-Ray 1080p disc will have one or two layers, a single layer disc has a maximum capacity of 25GB, a dual layer disc 50GB. This can be considered equivalent to a DVD5 vs DVD9. A Blu-Ray 4K disc will have either two or three layers.
A standard Blu-Ray 1080p disc will typically use the H.264 codec, a UHD disc will typically use the H.265 codec which is roughly twice as efficient.
Blu-Ray UHD discs have additional DRM protection over 1080p discs. I believe this does involve some hardware differences in the drive. However I also believe it has already been defeated or equally likely if you have a Blu-Ray drive physically capable of reading the third (additional) layer and hence is hardware compatible then you can use that drive to also defeat the remaining software protections. I recall reading originally that this requied a desktop PC with a SATA connection rather than USB. However external USB drives typically have a SATA connection in the enclosure so this may no longer be an issue.
I believe the Blu-Ray ‘menu’ is the same on both 1080p and 4K titles, so a player that can understand the structure of a Blu-ray Disc can play both as long as it also has both H.264 and H.265 codec support.
So if you have a suitable three layer drive and a tool to crack the DRM and a player to play H.265 you may be good to go.
Note: Cracking the DRM is a crime in many countries.
VLC has some support for playing Blu-Ray menus and does support both H.264 and H.265 codecs. VLC itself does not have the ability to bypass the DRM. However if some other tool has copied the contents and defeated the DRM then VLC can play it. I find VLC’s Blu-Ray menu support to be flakey but better than nothing. You can in theory bypass the menu and play the main title directly.
Note: I also found and reported a bug in VLC’s DVD menu support but they don’t seem interested even though it affects all versions of VLC i.e. Mac and Windows. This is the fact that it does not read the language setting of the device the player is running on and pass this as a variable to the DVD menu so that the DVD disc also defaults to that same language. As a comparison both Windows and Apple DVD players do this correctly although VLC on Mac and Windows does not. Annoyingly this results in my Stars Wars Episode IV disc defaulting to French instead of detecting and using English. (Merde!)
For those who may say why not just use streaming or something like the iTunes Store? It is still the case that the video and audio quality of a genuine Blu-Ray 1080p or UHD disc is superior to either streaming or a download purchase particularly with regards to audio options as Blu-ray Discs can have lossless audio tracks. Also a disc may have numerous extras. In terms of life space I would rate both equal, a streamer or store may go bust or discontinue the title, a physical disc may fail.
Note: I share what seems a majority view that Apple’s own streams in 4K are generally higher quality than others but still do not include lossless audio.
Your first point (the physical format - number of layers and the capacity of each layer) is what will make many (most? all?) UHD media incompatible with BD-ROM drives not designed for UHD.
Your other differences (CODEC, DRM, menu system), while definitely important, will primarily affect your video playback software, not your choice of drive.
And there are already apps available to play UHD movie discs. But as you point out, the free one (VLC) can be squirrelly at times. And those produced with licensed software (to be able to legally play the content) can cost more than a physical player.
Correction. The app I was thinking of, Macgo Blu-Ray Player Pro doesn’t support UHD. Only HD Blu-Ray discs. And it costs $65.