Comment by 201984
The classic distinction is that a CISC has data processing instructions with memory operands, and in a RISC they only take register parameters. This gets fuzzy though when you look at AArch64 atomic instructions like ldadd which do read-modify-write all in a single instruction.
That's more "load store architecture" than RISC. And by that measure, S/360 could be considered a RISC.