Well there is a gradation between bipolar and schizophrenia such as bipolar with psychotic features (where a person experiences psychotic symptoms specifically during moodswings) and schizoaffective
disorder, as was mentioned as I have where if untreated a person experiences
psychotic symptoms at all times. Bipolar in some people can worsen over a life time, certainly if untreated and there are many subtypes of bipolar, including bipolar with psychotic features.