Not alltogether right, but close.
Extended-Density disks were 2880M ( twice the density of HD disks). These were however used only in select few machines (notably IBM and NeXT)
additionally....
PC Formats were
High density 3.5" was 1.44MB, and HD5.25" was 1.2MB
Quad density 5.25" was 720K
Double density 3.5" was 720K and DD5.25" was 360K
5.25" also came in Single-Sided variants at half the capacity.
If you happened to have a SS drive, you could buy a puncher that punched id-holes on the "other side" of the disks so that you could flip them over and use the other side. This was common in the Apple //e and Apple ][, ][+
Atari used the PC format.
Amiga used 880KB DD-disks with a proprietary formatting, and also offered 1760KB with HD-disks.
The Machintosh used 800KB disks
Currently I have about 200 disks for my Amiga, 100 disks for my Archimedes, 20 3" CF-disks for my Amstrad CPC and several disks for DOS, C64 and more. "And they ain't goin' nowhere" (yes, I know, double negation et al. It just sounds cool when you say it with a southern accent ;) )