Being message-driven is the core of reactive microservices. All reactive microservices define, as part of their behavior, any event that they might be generating. These events may or may not have additional information payload with them, depending upon the design of the individual event. The microservice that is the generator of this event would not be bothered about whether the event generated was acted upon or not. Within the scope of this specific service, there is no behavioral definition for the action beyond the generation of this event. For it, the scope ends there. It is now for the rest of the system comprising other microservices to act upon this information, based upon their individual scope.
The difference ...