Although both are mental health conditions, ADHD and bipolar disorder are two very different illnesses. Impaired executive functioning makes it harder for ADHD affected individuals to focus, prioritize tasks, keep track of time, and hold back certain impulsive behaviors.
On the other hand, people with bipolar disorder can experience severe shifts in mood, energy, and emotions. These people often change from euphoric, or manic highs to crushing fits of depression.
It is not fully understood what causes bipolar disorder, although studies have found a correlation among family members.