What is the difference between Microsoft Azure Digital Twins and Microsoft Azure IoT Central? When to use what?

I am trying to understand and try out the IoT Service Stack on Microsoft Azure. When reading through documentations and blogs i came across the Microsoft Azure Digital Twins and Microsoft Azure IoT Central service.

But what i didnt understand is:

• What is the difference between Azure Digital Twins and Azure IoT Central?
• When to use what?
• Run combined? Is there any scenario for this or is there a need to use both in parallel? Any scanario for this?

Azure Digital Twins
https://azure.microsoft.com/de-de/products/digital-twins/

Azure IoT Central
https://azure.microsoft.com/de-de/products/iot-central/#overview

You could write a lot about the differences between these products, because they serve a different purpose.

Azure IoT Central is a Software as a Service application that allows you to register, manage and control devices. It stores the device state and provides bi-directional communication between the application and the devices. It's based on Azure IoT Hub for communication and Device Provisioning Service for device registration.

Azure Digital Twins (ADT) is a Platform as a Service offering that allows you to model anything using the Digital Twin Definition Language. While this language is also used in IoT Central to create device templates, the language can be used in ADT to model anything from buildings to people. ADT is used to create a graph-based information model that can be updated through the API. So if you want to include device data, you will need IoT Central or IoT Hub and write code to connect it to ADT. You can use any other data that you have and do the same. It's not limited to IoT devices.

In short, use IoT Central if you want a SaaS platform to manage devices and display telemetry. Use ADT to create a graph-based data collection using any input data you want.

> Is there any scenario for this or is there a need to use both in parallel? Any scanario for this?

ADT needs information from a source. This could very well be IoT Central. You can export telemetry from IoT Central and populate the graph. There is no standard way of doing this.