What is the difference between autism and Asperger's?

"My source for my answer to this question is Dr. Kenneth Roberson,Ph.D, who is a clinical psychologist in San Francisco with 30 years of experience evaluating and treating adults with Asperger's Syndrome and Autism Spectrum Disorders(ASD). According to Dr. Roberson, there are three main differences between Asperger's and autism. Compared with classic autism, people with Asperger's have IQ's that fall in the normal or even superior range. Those with autism typically have lower intelligence, as measured by standard assessment measures. Speech is the second difference. People with autism do not typically develop the normal abilities to use sounds and language as means of communication whereas the speech of those with Asperger's is intact. They may not understand the subtleties of language, such as irony and humor, or understand the give-and-take nature of communication but their ability to speak is intact, whereas that is not the case with autism. The third difference if the age of detection. Typically, Asperger's becomes noticeable when the child enters school and difficulties with socialization become apparent, whereas autism is generally observable by two years of age, even earlier, when persistent failure to engage with people is observable." Answered by Marsh England,Special Education Teaching Assistant at Elementary School and Elementary Schools(2014-present) on Quora