Just the way I see it . . . and for accurate descriptions a message to Scanavo is the way to go.
ZERO VARNISHED = POLISHED MATTE
Best of both worlds (IMO) and used ideally for fine detail steelbooks to give that extra kick that plain matte Matte may not provide - at the same time keeping all the fine detail which might be "lost" if a full Gloss varnish is applied.
https://translate.google.com/transl...ro-finish-de-certains-steelbooks/&prev=search for a brief, interesting article - with pics - of the differences between Matte and Zero.
SATIN VARNISH = MATTE GLOSS
Almost as if a Matte steelbook has been given a layer of Gloss varnish followed by a layer of Matte varnish to tone it down giving it a "silky' appearance but still with a sheen but a muted sheen when compared side-by-side to a Zero finish.
Jury's out on which finish is the "best in show" as each has specific qualities that the others do not have and a particular finish may suit a particular steelbook better depending on several factors (and not my place to go into the minefield of Gloss vs. Matte vs. this that and the other here).