Plain read/write (UDRW), sparse image (UDSP), and sparse bundle (UDSB) compared for storage efficiency, performance, and convenience.
sparse image
All you need to know about the sparse RAW disk images used inside lightweight VMs on Apple silicon Macs.
In Monterey and Ventura, regular read-write UDRW disk images can now be APFS sparse files, and work more efficiently than sparse images or sparse bundles.
Disk images originated in the 1960s, and are still valuable tools in modern macOS. They have their limitations, though, and in some cases should be replaced by APFS volumes.
They have more options than most new cars. What are they, how do you use them, how to pick the most appropriate, and which tools to use.
The Eclectic Light Company 