This is in part because the term "Asperger Syndrome"[1] (which has always been related to / a subtype of autism) is no longer used and is now just under the Autism label.
Together with PDD/NOS (which is an entire category on its own, because you also could be diagnosed with this if you "just" have brain damage, leading to autistic like symptoms), Childhood disintegrative disorder, and Rett syndrome.
But to simplify diagnosis they swept it all up and since DSM V was released all those things are now under the ASD (Autism Spectrum Disorder) umbrella
[1]: https://en.wikipedia.org/wiki/Asperger_syndrome