What's the difference between a beginner class and an advanced class? What is different in what is being taught?
You probably have a snarky response already planned out, but I'll give you a serious answer.
The advanced class might teach a sequence that involves some kind of anticipation followed by some detailed counter. Let me give an example "advanced" technique..
The instructor lays out the scenario:
You are going for some sort of smash pass (the advanced students know this pass already) and your opponent does a particular counter - let's say that they push on your head a certain way. When the instructor shows this counter, the advanced students all nod in agreement as it is something they've encountered numerous times.
So, the instructor shows a technique to counter this head push. This counter-technique involves fencing your feet (the advanced students know how to fence already), sitting out (the advanced students know how to sit out already), and popping up to KoB (the advanced students know how to transition and maintain KoB already) on the opposite side.
Why would this be inappropriate for a white belt?
a) The white belt doesn't know the original smash pass
b) The white belt doesn't know how to fence their feet
c) The white belt doesn't know how to sit out
d) The white belt doesn't know how to transition to and maintain KoB
So, in the beginner class you learn a,b,c, and d in the simplest way possible -- isolated -- rather than within some complicated chain of techniques that only works for a particular scenario.
Even with things simplified in such a way, it's not until the middle of blue belt that you feel reasonably confident in a,b,c, and/or d.
FWIW:
I'm only a purple, but in my experience many (perhaps 50%) of the techniques taught in the advanced class will not ever be used by a given student. All of the beginner class techniques continue to be used by everyone, however, based on my experience and in talking with veterans of the game.