I felt like I should really attempt to back up some of what I wrote earlier with more than just "I believe I remember". In my post above, I mentioned that I learned (and personally experienced) that though hallucinations of various types are common in extreme episodes of bipolar disorder, that delusions are particularly common. In Prevalence and description of psychotic features in bipolar mania. - PubMed - NCBI it says "Grandiose delusions are the most common type of psychotic symptom [in bipolar disorder], but any kind of psychotic symptom, including thought disorder, hallucinations, mood-incongruent psychotic symptoms, and catatonia can present as part of a manic episode."

"Thought Disorder" as mentioned above as a possible bipolar psychosis symptom, is common in schizophrenia, too. I don't often read about this psychotic symptom for bipolar disorder, but in extreme psychosis I think it happens a lot. I have definitely experienced this. There is a helpful description at Thought Disorder | Johns Hopkins Psychiatry Guide A couple of the characteristics (an interesting list) are seen in various levels of mania, but my assumption is that when they get particularly severe it is on the level of psychotic.

In an article by John M. Grohol, Psy.D. published right here at Psych Central, he writes "Most people with schizophrenia experience auditory hallucinations, particularly hearing voices, and about one-fourth of those with the disorder experience visual hallucinations." That article can be found at Ever Wonder What a Visual or Auditory Hallucination Was Like?