What are the different types of bipolar disorder?

The American Psychiatric Association's Diagnostic and Statistical Manual Fourth Edition (DSM-IV) has divided bipolar disorder into two types, Bipolar I and Bipolar II, both which are severe and debilitating. In addition, the DSM-IV lists as separate disorders "Cyclothymia," which can be described as a "bipolar lite," and schizoaffective disorder, which borders on schizophrenia.