Explanation:

Box 1: Premium
Service Bus can now emit events to Event Grid when there are messages in a queue or a subscription when no receivers are present. You can create Event Grid subscriptions to your Service Bus namespaces, listen to these events, and then react to the events by starting a receiver. With this feature, you can use Service Bus in reactive programming models.
To enable the feature, you need the following items:
A Service Bus Premium namespace with at least one Service Bus queue or a Service Bus topic with at least one subscription.
Contributor access to the Service Bus namespace.
Box 2: Contributor
Reference:
https://docs.microsoft.com/en-us/azure/service-bus-messaging/service-bus-to-event-grid-integration-concept

Explanation:

Explanation:

Box 1: WebJobs
A WebJob is a simple way to set up a background job, which can process continuously or on a schedule.
WebJobs differ from a cloud service as it gives you get less fine-grained control over your processing environment, making it a more true PaaS service.
Box 2: Flow

Explanation: