Introduction
You can use Microsoft Graph to connect and integrate your web service or software as a service (SaaS) solution with Dynamics 365 Business Central. With Microsoft Graph, you can build apps that get authorized access to and integrate seamlessly with all supported Microsoft products in a single endpoint. This simplified experience also integrates with Business Central data.
A Connect app establishes a point-to-point connection between Business Central and another solution or service and is typically created by using standard REST API to interchange data. Coding language that is capable of calling REST APIs can be used to develop your Connect app.
Along with the existing OData and SOAP web service, Business Central also supports an API system. If you ever want to connect to Business Central, you should preferably use the API system above other web services. The Business Central API allows you to read and modify business data through apps that are connected and integrated through a single endpoint. For example, you can use the API to get access to customer and vendor information, update sales orders, or view overdue payments. Because the API uses standard REST and supports OData to query the results, you can use the same OData Query options.
The main difference is that you need to create separate pages and queries to use them in the API instead of reusing existing objects in OData web services. API objects are specifically created for API usage only.