Great share! I've been researching this on and off for about a year and half and he touched on almost all of the major points I've seen scattered around pretty well.
These recent reviews of AVPD [1
] cover much of the same ground in more detail, plus some other topics. So I'll just add a few points and sources to clarify.
1. The primary distinction between them, in my opinion, can be summarized as AVPD being existential
and SAD being situational
. Lisa Lampe's clinical observations
echo the deeply negative sense of self mentioned by Dr. Grande and in the above reviews -- a feature that's not part of SAD except for low self-esteem being a possible consequence
. People with AVPD conceive of themselves as irredeemably flawed and alienated from others, thus carrying deep anxiety, shame and anger. Their very personalities are infected, so to speak, by the illness (as per the definition of a PD); who they are
becomes a problem for them.
In contrast, SAD revolves more around particular feared social situations
and how to navigate them. Low self-esteem can be part of the causes and effects of SAD, however. But as Lampe observed, their negativity towards themselves is about things accidental to who they are, unlike the AVPD patients. So people who are otherwise very assured in themselves can still struggle with social anxiety, as a friend of mine is and does. Hence, as Dr. Grange explained, socially anxious people find their problems coming up more cyclically since it's rooted more in circumstances, which are mostly discrete and changing -- unlike one's sense of self.
2. Personality vs anxiety disorder. Dr. Grande repeated the official conceptualization of personality disorders as being relatively stable over a lifetime. While this is true here to the extent that social anxiety is more environmentally contingent, personality
still predisposes one to social anxiety; the distinction doesn't well account for chronic mood and anxiety disorder cases, such as people with lifelong SAD; and personality disorders have been found to be less stable than assumed. For instance, AVPD and PD symptoms in general have been found to get milder around and after middle-adulthood, rather than being stable or progressive across life.