There is a lot of overlap, but with ASD, the diagnosis is based around social communication difficulties, and rigid/repetitive behaviour, rather than sensory sensitivities. ASD is more like a cluster of disorders to form a certain profile - social communication issues together with some OCD traits, some ADHD traits and some SPD traits, whereas, obviously, SPD is only related to sensory issues.
I have social communication difficulties plus I have some, but not all, SPD traits (but not actual SPD ?); some, but not all OCD traits (but I don't have have OCD?), some but not all ADHD traits (but not ADHD?) I put a question mark on these, because I haven't been officially tested for these and it's still possible that I may have them to such an extent to warrant a diagnosis.