Similiarities/differences in AS and BPD?

I´ve now read about at least a handfull of people who, while looking for the cause of some of their personal problems, found themselves being unsure about whether it might be AS or BPD. How comes? In which way are they related? Or, if they´re not, what could lead people to think they are? What makes the two look similiar? Where are differences? I always thought of them as the opposites on a scale. I´m not so much interested in neurological backgrounds, but the way the two present and are perceived.

-Camelidae


P.S. Started the same thread in the Asperger forum, but thought you might have some ideas as well.