@ everyone in here I also found in this book that AvPD is often diagnosed with social phobia with the generalized type.... with Dependent personality disorder...with borderline personality disorder and with the cluster a personality disorders (paranoid, schizoid or schizotypal personality disorder).
In my opinion AvPD is realated with different types of disorders.
I know but we are discussing about these two disorders, I think SAD is fear of some specific social situations, and AvPD is fear of social situations in general with a combination of others disorders.