Asperger's can be mistaken for shyness, especially in girls. This was definitely the case with me. All my social problems were attributed to shyness, even things that had nothing to do with being shy. But a professional would not make this mistake. Many people with Asperger's are actually not shy at all; they struggle with social situations because they lack social understanding. And there are many other symptoms of Asperger's as well - difficulty reading people, obsessive interests, need for routine, repetitive behaviors, poor motor coordination, abnormal sensory processing, etc. On a professional level, Asperger's and shyness would not be confused.
Most shy people do not have an autism spectrum disorder, though, or any other disorder. Like I said, there are many other symptoms that are required for a diagnosis.
I have Asperger's