AS and SAD are distinct diagnostic categories. Many with Asperger's experience social anxiety, but many do not and are socially outgoing.
Here are the DSM-IV criteria for Asperger's; there are more than just social symptoms:
A Qualitative impairment in social interaction, as manifested by at least two of the following:
(1) marked impairments in the use of multiple nonverbal behaviors such as eye-to-eye gaze, facial expression, body posture, and gestures to regulate social interaction
(2) failure to develop peer relationships appropriate to developmental level
(3) a lack of spontaneous seeking to share enjoyment, interest or achievements with other people, (e.g.. by a lack of showing, bringing, or pointing out objects of interest to other people)
(4) lack of social or emotional reciprocity
B Restricted repetitive & stereotyped patterns of behavior, interests and activities, as manifested by at least one of the following:
(1) encompassing preoccupation with one or more stereotyped and restricted patterns of interest that is abnormal either in intensity or focus
(2) apparently inflexible adherence to specific, nonfunctional routines or rituals
(3) stereotyped and repetitive motor mannerisms (e.g. hand or finger flapping or twisting, or complex whole-body movements)
(4) persistent preoccupation with parts of objects
C The disturbance causes clinically significant impairments in social, occupational, or other important areas of functioning.
D There is no clinically significant general delay in language (E.G. single words used by age 2 years, communicative phrases used by age 3 years)
E There is no clinically significant delay in cognitive development or in the development of age-appropriate self help skills, adaptive behavior (other than in social interaction) and curiosity about the environment in childhood.
F Criteria are not met for another specific Pervasive Developmental Disorder or Schizophrenia.
Here are Gillberg's criteria for Asperger's:
1.Severe impairment in reciprocal social interaction
(at least two of the following)
(a) inability to interact with peers
(b) lack of desire to interact with peers
(c) lack of appreciation of social cues
(d) socially and emotionally inappropriate behavior
2.All-absorbing narrow interest
(at least one of the following)
(a) exclusion of other activities
(b) repetitive adherence
(c) more rote than meaning
3.Imposition of routines and interests
(at least one of the following)
(a) on self, in aspects of life
(b) on others
4.Speech and language problems
(at least three of the following)
(a) delayed development
(b) superficially perfect expressive language
(c) formal, pedantic language
(d) odd prosody, peculiar voice characteristics
(e) impairment of comprehension including misinterpretations of literal/implied meanings
5.Non-verbal communication problems
(at least one of the following)
(a) limited use of gestures
(b) clumsy/gauche body language
(c) limited facial expression
(d) inappropriate expression
(e) peculiar, stiff gaze
6.Motor clumsiness: poor performance on neurodevelopmental examination
Here are the DSM-IV criteria for social phobia:
A. A marked and persistent fear of one or more social or performance situations in which the person is exposed to unfamiliar people or to possible scrutiny by others. The individual fears that he or she will act in a way (or show anxiety symptoms) that will be humiliating or embarrassing.
Note: In children, there must be evidence of the capacity for age-appropriate social relationships with familiar people and the anxiety must occur in peer settings, not just in interactions with adults.
B. Exposure to the feared social situation almost invariably provokes anxiety, which may take the form of a situationally bound or situationally predisposed Panic Attack. Note: In children, the anxiety may be expressed by crying, tantrums, freezing, or shrinking from social situations with unfamiliar people.
C. The person recognizes that the fear is excessive or unreasonable. Note: In children, this feature may be absent.
D. The feared social or performance situations are avoided or else are endured with intense anxiety or distress.
E. The avoidance, anxious anticipation, or distress in the feared social or performance situation(s) interferes significantly with the person's normal routine, occupational (academic) functioning, or social activities or relationships, or there is marked distress about having the phobia.
F. In individuals under age 18 years, the duration is at least 6 months.
G. The fear or avoidance is not due to the direct physiological effects of a substance (e.g., a drug of abuse, a medication) or a general medical condition and is not better accounted for by another mental disorder (e.g., Panic Disorder With or Without Agoraphobia, Separation Anxiety Disorder, Body Dysmorphic Disorder, a Pervasive Developmental Disorder, or Schizoid Personality Disorder).
H. If a general medical condition or another mental disorder is present, the fear in Criterion A is unrelated to it, e.g., the fear is not of Stuttering, trembling in Parkinson's dsease, or exhibiting abnormal eating behavior in Anorexia Nervosa or Bulimia Nervosa.
Specify if: Generalized: if the fears include most social situations (also consider the additional diagnosis of Avoidant Personality Disorder)