Difference betweeen Autism and Asperger
Aspergers is a mild form of autism. In general, aspergers is associated with social awkwardness, possibly some OCD-like behaviors, and sometimes sensory issues. Autism is a much more severe case of these symptoms, and some additional symptoms on top of them. Most people with Aspergers are able to function in the "normal" world but are probably labeled "weird" because of their difficulties with social situations. There are varying degrees of Autism from very high functioning to almost completely unable to do things for themselves.
I am not a medical professional, so please do additional research if you feel your child has Autism or Asperger Syndrome, this is just a brief overview of what I have learned through my mom who works at a special needs school.