The main difference between a mental disorder and a behavioral disorder is that mental disorders typically involve much more than problem behaviors.  Mental disorders are characterized by problems with thinking, feeling, and behaving that cause significant distress or impairment in important areas of functioning.  Behavioral disorders are characterized by recurrent problematic behaviors that may result in difficulties with attention, hyperactivity, and impulsiveness. Someone with a behavioral disorder may behave in ways that are disruptive or undesirable, but they do not usually experience the changes in thinking and feeling that are typical of mental disorders.