People can have schizophrenia and not hear voices. Besides having hallucinations and delusions, people can have paranoid ideas. They might think that people are against them, that people are conspiring against them, that the mail man's not really the mail man, but might be the mafia keeping an eye them and so on. Schizophrenia is not split personality. Schizophrenia is a severe, significant psychiatric illness.
Manic depression is the common name that's used to describe bipolar disorder.
People with bipolar disorder have mood swings. Most commonly they get depressed recurrently. But sometimes they get what's called manic. I once had a gentleman, he was 72 years old and he went to the pool hall in November, didn't come home until February. It's quite common for people who have a severe, very high mania to have psychosis.