Now with Catalina and its strange paired System and Data volumes, it just seems a bewildering mess. Then came High Sierra and Mojave with APFS, which complicated that with features like containers, and the simple illusion offered in the Finder didn’t bear much resemblance to what Disk Utility shows, and is further removed from Terminal’s shell. What we saw in the Finder and in Disk Utility was reasonably close to what we needed to use, and wasn’t too far from what you’d find using the diskutil command in Terminal.
Until Apple introduced APFS, the normal structure of our Mac’s disks and volumes was relatively simple.
