Autism and schizophrenia share coding mutations on a genetic level. Source:
https://www.nature.com/articles/s41467-021-25532-4
"Our findings imply that, in part, neurodevelopmental disorders and schizophrenia have shared molecular aetiology, and therefore likely overlapping pathophysiology, and support the hypothesis that at least some forms of schizophrenia lie on a continuum of neurodevelopmental disorders."
As far as I know, the autism/schizophrenia spectrum is fairly intertwined and symptoms from one disorder often overlap with symptoms from the other.
It's a balancing act of symptoms really, and whether which symptoms fall into which camp (autism or schizophrenia) that determines things from a diagnostic standpoint.