At least in theory, I don't really think this distinction makes much sense. As but the most obvious example, a number of Einstein's most fundamental papers (including special relativity, and mass-energy equivalence) were published as an "amateur", while he was working as a low level patent inspector. And this is from a time when knowledge was quite difficult to access, meaning there really was quite a meaningful distinction between "amateur" and "professional."
Now a days that distinction is largely gone. One can access effectively infinite information online, including access to educational resources from the most well regarded institutions that exist. One benefit of "amateur" science is that one can endlessly chase exceptionally improbable ideas. Publish or perish, bias against negative results, grants gained as a performance metric, and other factors mean the science that the overwhelming majority of academic researchers, let alone corporate, can pursue is quite limited.
Now a days that distinction is largely gone. One can access effectively infinite information online, including access to educational resources from the most well regarded institutions that exist. One benefit of "amateur" science is that one can endlessly chase exceptionally improbable ideas. Publish or perish, bias against negative results, grants gained as a performance metric, and other factors mean the science that the overwhelming majority of academic researchers, let alone corporate, can pursue is quite limited.