My pdoc explained it by saying bipolar people only have psychosis during mania or depression, while schizoaffective people can have psychosis when mania or depression is absent. However, he says schizoaffective is better than schizophrenia, which I suppose means not as severe, maybe, or perhaps psychosis is not as long lasting? I'm not sure what he meant, exactly. Some other people I talked to on the forums said that they've been told schizoaffective people supposedly have more insight than schizophrenic people.