The document discusses the similarities and differences between borderline personality disorder (BPD) and bipolar disorder. Both disorders involve unstable moods and impulsivity. However, they differ in the type of mood swings experienced. Those with BPD experience shifts between normal mood, anger, and anxiety, while those with bipolar disorder cycle between normal mood, mania, and depression. The presence of past trauma such as sexual abuse can help distinguish between the two diagnoses as BPD is often associated with trauma. The author questions whether a history of trauma could determine whether a patient receives a diagnosis of BPD or bipolar disorder.