Simple spacer Vs Super spacer

I hope you get a good answer. I have looked at the Super Spacers recently, but just now looked up a "simple spacer". Besides weighing about twice as much, it appears to me that the super spacer has a vernier whereas the simple spacer does not.

One of the things that I thought to be a limiting feature of these machines is that they are usually a 24 position machine, whereas an indexing head allows many more divisions. But then the "spacers" usually seem to have masking plates which, for me, would make it a lot harder to screw up when they are being used in rapid production.

Pete Stanaitis

Jim D> What is the difference?