I guess, difference is servo technology,
1.44 Mb floppy rely on mechanical servo system and
20, 120 Mb floppy rely on optical servo embedded on diskette itself
to more elaborate servo system to accessing data.

Peter C.
Wirt Atmar wrote in message ...
>Denys writes:
>
>> Let's see the endorsements Wirt lists are NeXT, Mac and SGI.  I wouldn't
>>  call those vigorous endorsements.
>
>They were actually a pretty big deal at the time.
>
>
>>  On the other hand the LS-120 is a 3M (Imation) product.  Many PC
companies
>>  offer it as an option, especially on laptops.  Compaq, IBM and several
>>  others also offer it on desktops.  When it is connected via ATAPI, it is
>>  quite speedy.  Connect it to the parallel port, and it's a different
story.
>>
>>  Will it last? Who knows.  Is it useful?  To me it is.  I have it for my
>>  laptop and I have stored the floppy drive somewhere.
>
>It's important to understand that the same people (3M) who brought us the
21MB
>Floptical are also the people who designed the 120MB SuperDisk (all they
did
>was change the name from "floptical" to "LS-120", where LS now stands for
>"laser servo").
>
>While they continued to make the LS-120 format compatible with the
"standard"
>1.44MB floppy format (essentially because they felt they had to), they
didn't
>make it compatible with their own prior 21MB floptical format, which is
enough
>to make some people a little grumpy (me included).
>
>As for endorsements, IMATION (a 3M splitoff, a la the "new" HP) has a
>superdisk web page that repeats almost identically the same marketing spiel
>they wrote in the early 1990's. The URL of interest is:
>
>      http://www.superdisk.com/ms/ms_fq.html
>
>Technology may evolve, but marketing text doesn't have to :-).
>
>
>>  Sony has released the 200 MB floppy drive, which can also read/write
1.44MB
>>  floppies.  So now, it's going to be a battle between Zip drives, LS-120
>>  drives and the Sony HDHD.
>
>This is really the core of the problem. Technology moves on -- and at the
>moment never really gets a chance to grab a substantially majority of the
>market to dictate that the "current" standard be supported any more than
just
>a few years -- before the next "wave of the future" arrives on the scene.
>Sony's 1.44MB original format had that chance -- and because of it --
became a
>defacto standard that "had to be" supported.
>
>Wirt Atmar
>