Let me give this a try...
The Zanerian holder was developed by the
Zaner Bloser (for the Zanerian College).
Del Tysdal then began to make and sell his own in different lengths and woods based on the original and most recently both PIA and John Neal also started carrying their own (not sure if it's associated with ZB or Del Tysdal).
However, most often, when someone refers to a holder as a Zanerian style they are referring to the way the flange is mounted. Zanerian mounted holders (im assuming they were the first to offer this) are those with the flange held in place by drilling a hole, inserting the flange and holding it in place with a shim--such as pens turned by Brian Smith and Bill Lilly while the other primary style is the pin and glue method used in the PIA Hourglass Adjustable and those made by Michael Sull, Jake Weidmann and Chris Yoke (I'm not sure but Held holders might be this way as well). These are the two primary methods used with custom/wood holders but of course there are variations. Most mass produced plastic holders are either pin/glued or just glued in place and then there are the unique ones like the all wood Blackwell which has it's own style.
I'm including a close up of both. Zanerian (hole drilled and slot cut half way for flange, flange has tabs to hold it in place once it's shimmed) on the left and Pin/Glue (slot cut all the way through and pin hole drilled at a diagonal to hold in place) on the right.
If you heard it in a different context let me know, I'd love to hear what other say. I personally prefer the Zanerian mounted holder because I like to adjust and use my own flanges which are very easy to remove vs the pin/glue method. Although I'm sure if I had the right tools I might change my mind