They are similar, the main difference is that Ponzi schemes rely on the promise of returns on investments (while being paid out by future investors) where pyramid schemes rely on getting new recruits to bring in the new money.

In a practical sense they are probably interchangeable.

The point I was getting at is that crypto markets operate on "supply and demand" a demand that really only increases as more people sign on, invest money or add value to these systems. Where nothing in them as any real inherent value. (Yes, there's value in the algorithm, the exchanges, the similarity to currencies in transactions, but if the blockchain shut down for whatever reason that value evaporates with it).