The difference is that there is no special thing called 'collapse'; when you write down the laws of physics, it doesn't exist. It's an emergent phenomenon, and

The difference is that there is no special thing called 'collapse'; when you write down the laws of physics, it doesn't exist. It's an emergent phenomenon, and it's not surprising that it happens, although it's very counterintuitive _if_ you are starting in the naive model of treating quantum waves like classical ones.