system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is autism considered a spectrum disorder? Why are Asperger syndrome and profound autism where someone must be constantly monitored considered the same condition?
gpt
It pretty much used to be seen as one condition when it was even more poorly understood than it is now. There are some common traits like social difficulties relating the entirety of the spectrum but generally speaking two different people on the spectrum can be as different as two people not on the spectrum. As we understand more and more about these conditions, terminology changes. Different attempts have been made to categorise different presentations, but none have been quite accurate enough. Describing autism as a spectrum is just the next improvement made in an effort to help diagnostics and treatment. 

Also don't listen to the other guy saying autism is caused by chromosomal deformities. There's strong evidence that there's a genetic component involved in autism, but we have no idea what it is. Could be a single gene, could be many genes interacting with each other.