How does one distinguish BPD anger from ADHD anger? Some people with ADHD are known to have difficulties in controlling anger.

Whenever a person with ADHD has difficulties in controlling anger, how does one determine whether or not that person really has BPD? By which I mean to ask, how do we know that the anger is symptomatic of BPD rather than ADHD?
Borderline Personality Disorder (BPD) is a complicated diagnosis to understand and treat. A painful mix of emotional trouble, unstable relationships and self-destructive behavior, including suicide attempts are associated with BPD.

Experts have given a new name to BPD as Biosocial disorder. People who develop BPD are highly emotional, sensitive and reactive, more immediately and intensely than most people. And once a powerful emotion is triggered, it takes them longer to return to their emotional baseline.

Attention Deficit Hyperactivity Disorder (ADHD) is a chronic condition which includes attention difficulties, hyperactivity, and impulsiveness.

ADHD is often seen in childhood persisting into adolescence and adulthood, which contributes to hyperactivity, low self-esteem, disturbed relationships and attention difficulties at school or work.

In relation to anger, individuals with BPD report higher traits of aggression and hostility when provoked than individuals with ADHD.

Furthermore, individuals with BPD exhibit a higher state of anger and stress-dependent anger increase. In BPD patients, aggression and anger were positively correlated with emotion regulation deficits.

Being a Special Education Teacher at Accel Centre, there are kids and adults with special needs education who require vocational training for special needs that helps them to develop social skills and anger management.

Reference: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5356413/