It's not early, but conflicting: "conflicting"/paradoxical findings.

Biochemically, there probably are more differences, but also overlap. It's difficult. Two opposing (types of) theories.

What makes it extremely difficult is that ASD overlaps with SZ and BP (the syndromes, objectively). So there's likely a lot of misdiagnoses or "inherently" invalid/immaterial diagnoses.

Autism used to be a part of schizophrenia, just a subset of its symptoms. So arguably, there are two (underlying, endophenotypical/genetic) autisms.

I strongly believe in the "diametrically opposed" theory of ASD and SZ/BP. That would mean there are a lot of misdiagnoses.

That ASD is overdiagnosed may in part be (it's very likely) that ASD is considered neurodevelopmental, unlike SZ/BP. In pretty much all cases, for mental disorder diagnostics, a diagnostic hierarchy is used, where organic disorders, like ASD, take precedence over functional psychoses, like SZ/BP. In other words, if ASD is "discovered" the clinician/diagnostician doesn't have to look further.

Another reason (for misdiagnoses) may be that ASD can be diagnosed faster than BP/SZ, since it's not episodic.

Basically, there are a lot of people with "ASD" and psychosis. There are. That doesn't make sense.