In my mind they are all the same. But some serious physicists (Schlosshauer, for example) claim there is no evidence for the existence of collapse. What about Lyman alpha emission, where an electron in a hydrogen atom “jumps” from level two to level one and emits a photon? Or the photoionization effect, or a Stern Gerlach experiment? Those all seem to me to be very obvious demonstrations of the existence of collapse. What am I missing? Or what would the no-collapse people reply?