Explanation:
Box 1: Dual-write
When a work order is created, Dynamics 365 Field Service must create a sales order for that work order in real time.
Integrate Dynamics 365 Field Service and Supply Chain Management
How it works
The integration is made possible because Field Service is built on top of Common Data Service and dual-write, which writes changes in Dynamics 365 Supply Chain Management to Common Data Service and vice versa.
After dual-write is enabled, a solution is imported into Field Service that adds the required fields to make the entities in each system integratable.
Box 2: Business events
A user creates a change-based alert that will trigger when a newly created sales order from a workflow is greater than $5,000. The alert must trigger a workflow the user can modify to automate other steps.
Business events provide a mechanism that lets external systems receive notifications from finance and operations applications. In this way, the systems can perform business actions in response to the business events.
Business events occur when a business process is run. During a business process, users who participate in it perform business actions to complete the tasks that make up the business process.
A business action that a user performs can be either a workflow action or a non-workflow action. Approval of a purchase requisition is an example of a workflow action, whereas confirmation of a purchase order is an example of a non-workflow action. Both types of actions can generate business events that external systems can use in integration and notification scenarios.
Reference: https://learn.microsoft.com/en-us/dynamics365/field-service/supply-chain-field-service-integration
https://learn.microsoft.com/en-us/dynamics365/fin-ops-core/dev-itpro/business-events/home-page