Aspergers and autism were defined in the DSM 5 as being on the same spectrum, because the symptoms for Aspergers are indistinguishable from autism: except Aspergers is the mildest form autism takes.
They are the same, but also not. It's a spectrum.
Also people want to distance from the Aspergers name because the guy it was named after was a doctor who sent autistic people he deemed "not useful in society" to the gas chamber. People who were diagnosed as having Aspergers Syndrome were deemed "useful", and people were who diagnosed as "autistic" were the ones gassed.