> They required a dedicated zip drive (took up same sized slot/bay as a floppy disk drive), but (if I recall right) that drive was backward compatible standard 3&1⁄2-inch 1.44MB floppy disks.

Zip was a completely unique physical format, and had no backwards compatibility with standard 3½" disks.

SuperDisk, on the other hand (in both the LS-120 and LS-240 variants) was backwards compatible with standard floppy disks in the same drive.