I guess they're more-or-less interchangeable. From what I hear, "operator" is generally used to refer to Yamaha FM (and I sometimes use it for FDS/etc. FM as we

I guess they're more-or-less interchangeable. From what I hear, "operator" is generally used to refer to Yamaha FM (and I sometimes use it for FDS/etc. FM as well), while "oscillator" can describe essentially all synthesizers.