Often times you here it suggested on here that they're polar opposites. In reality, they're just different diagnoses based on different things. Here are some symptoms people with ASPD, Sociopaths and Psychopaths often feel that are similar, if not the same as those with Borderline Personality Disorder:
- Feeling nothing/feeling empty. This may or may not include depression, but is usually in part a lack of feeling that life has a point, purpose and or value. Though BPDs, unlike ASPDs, tend not to be indifferent to this. It's usually an uncomfortable feeling to them, and BPDs often, but not always, try to run from this feeling by engaging in activities that can often be harmful to their health.
- Impaired capacity for empathy is also often present in BPDs
- Impulsivity is big for both groups
- A tendacy to have a bad temper.
- A tendacy towards selfishness, though not a symptom nor trait specifically named out for BPD, it is common in folks diagnosed as such.
- A pattern of unstable relationships
- Promiscuity
That's not to say that they're the same, they're different ways of dealing with the world, but they're not so different. It's just that BPDs tend to be more emotional. Reading the DSM-V criteria, I see why my old therapists used to think I had BPD. I still think both diagnoses are just labels though.