They're not definitionally the same. Normally a (stock market) crash is just "everyone's assessment of expected future cash flows goes down, meaning that what everyone owns is less valuable". One thing that can cause people's assessments to drop is "everyone else is withdrawing from it, which I assume means they're assessing it as being much less valuable, so they have information I don't, so I should revise downwards", which can make a self-sustaining feedback loop, but that's certainly not the only possible cause of a crash; I wouldn't even say it was the most likely cause of an AI-bubble crash.

My guesses would be "everyone's assessments go down together because OpenAI et al's predictions of their future revenue are observed to be consistently vastly overinflated vs actual performance, but everyone was previously assuming they were roughly correct" or "some political thing happens which makes OpenAI et al's services obviously much less valuable or makes them much less able to provide services".