BPMN doesn't quite differentiate between its activities in terms of "does this need user interaction" vs "process this thing".

User interaction is a distinct BPMN Activity Type, so BPMN can make this distinction quite unambiguously. Concrete BPMN implementations, IIRC, use varying amounts of the spec and have varying degrees to which Activity types are functionally rather than merely visual distinguished, so a particular BPMN tool may or may not make the distinction or treat it as significant.