The concepts bleed into each other, but Matt Levine explains it well. The Ponzi scheme is unsustainable. it gives you a solvency problem, your assets are bad and no amount of time will help. With fractional reserve banking run on banks usually come down to a liquidity problem, everyone wants their money now and you don't have all of it. So you call up someone with cash, like the FED, and theyll lend to you because you are a chartered, regulated bank.

basically the difference is asset quality and proper accounting. Banks are similar to ponzis, but they are HIGHLY regulated to ensure their continued operation.