Explain why impulsive personality disorder's classification is described as differing across diagnostic systems.

One major classification system groups it as a subtype of emotionally unstable personality disorder, treating the explosive, poorly controlled outbursts as one recognised pattern within that broader category, while another system treats it as a separate, non-personality-disorder category in its own right. Its favourable response to certain mood-stabilising and antidepressant medications has also prompted suggestions of a link to bipolar disorder, though this remains a matter of ongoing discussion rather than settled fact. This matters clinically because how the pattern is classified can shape which treatment approaches are considered first, even though the underlying clinical picture, explosive, disproportionate outbursts with a characteristic build-up and remorse, is described consistently regardless of which system is used.