THIS extremely informative slideshow on healthcentral.com answers a lot of questions about bipolar disorder in clear, simple terms:
Bipolar disorder is a mood disorder.
Bipolar disorder always includes mania.
Unipolar depression is not bipolar disorder.
Borderline personality disorder is not bipolar disorder.
Narcissistic personality disorder is not bipolar disorder.
Schizophrenia is a psychotic disorder, not a mood disorder.
Dissociative identity disorder is not bipolar disorder.