Supadriv is quite old now, I seem to recall it dates from the 80’s.
It’s more a difference in the screw than the driver. Supadriv screws were a fast driving twin thread design, and were designed to be driven without pilot holes, in an era when most screws were not.
I think the only difference in the screw head was to allow the supadriv screws to be used with push in screw covers, rather than needing different screws. But I also recall that you could use a No.2 driver with just about every screw, only the depth of engagement varying, which is why the drivers were slightly different.
Back then, Supadriv drivers could be used with Pozidriv screws, but not necessarily the other way around. I think now most Pozidriv drivers are compatible with Supadriv screws, but Vessal seem to be the only maker who offer dedicated Supadriv drivers.
Might have a few Supadriv screws around, but can’t recall the last time I saw them available new.
Edit - Here’s an original box with a selection of Supadriv screws and a matching driver. The drivers look like a Phillips to the unwary, as they don’t have the characteristic star shape wedges of the Pozidriv. You have to look very carefully at the front of the tip to see what it is. Personally I reckon this was a stupid idea and I’m not surprised it died!
Just for reference, my 80’s vintage Stanley Pozidriv fits fine. My similar vintage Snap On is a bit sloppy, but it’s one of my most used tools. All my newer Pozidriv drivers fit fine.
