There are two crucial differences. The first one is where the money goes. If they would cover the short, they buy the stocks for a large price on the open market and give the stocks back to the people who loaned them the stock in the first place - so the money goes to people who are currently holding that stock and would be willing to sell at that high price.

On the other hand, if they go bankrupt, then their assets are used to compensate (as much as possible) to everyone they owe in cash - not (as previously expected) in that stock. So the expected huge future purchase of the shorted stocks never happens, and all the WSB people who are holding the stock get to keep it or sell it to each other, as all that compensation money does not flow to the market for GME stocks as it would be if the shorts were actually covered. The brokers would be liable, and they might have insurance that might be liable, but all that liability would be cash-denominated and (as far as I understand - if I'm mistaken, please correct me) would not obligate anyone to buy any GME stocks.

The second big difference is in the timing. The current price is driven by short-term expectations, a hope that somebody is going to (or would be forced to) buy large quantities of that stock soon. If one of the shorting hedge funds goes bankrupt, then any settlement for that will take many months, and that money won't influence the market for that time.