What is the difference between avoidant personality disorder and social phobia?

I'm probably wrong but I think the difference is that the person with the avoidant personaity disorder is that they feel unwanted - and perhaps have a negativie emotional response to that and to having to be isolated. My friend who has been diagnosed has described it more as a loathing of social situations. Those on the otherhand with Social Anxiety experience a fear response to social situations.

Any other ideas out there?

As I understand, there is an element of fear in the avoidant personality disorder, too.