Just to clarify, for me at least. What is the difference? Cards cover one and hands cover the other? I always thought that Matrix was four coins moving around a table. Never looked so much into the rules.
Nestor Hato's routine "Hatrix" must have been done out of ignorance if Matrix is only covered by cards.
Speaking of ignorance... I'm sure Nestor Hato would agree that his routine is not completely original in plot, or style.
These aren't rules. It's nomenclature.
The word "Matrix" in this context refers specifically to Al Schneider's routine. It used cards. "Coin Assemblies" are also "four coins moving around a table", but are not "Matrix". If something uses an item other than cards, such as postcards, dollar bills, etc... It's still not "Matrix". It's an assembly.
It's like calling facial tissue "Kleenex". Only one brand can accurately be called that... The rest are simply "facial tissues".
Small differences are a big deal in a world with increasing quantities of available magic. It's good to learn the correct terminology, as a way to respect the innovators, creators, and originators of over done and often massacred effects and magical plots.
Scott.