At least in Postgres, table-valued functions can't take tables as arguments, only scalars. That's the main difference: functors can not just return tables, but

At least in Postgres, table-valued functions can't take tables as arguments, only scalars. That's the main difference: functors can not just return tables, but take tables satisfying some interface as arguments. https://www.postgresql.org/docs/7.3/xfunc-tablefunctions.html https://www.postgresql.org/docs/7.3/xfunc-tablefunctions.htm... I thought I had written a footnote or appendix about this but I guess I forgot.