Device and component

Both words appear in the controller, and they do not mean the same thing.

A device is what you added: a Shelly, a KNX actuator, a motion detector. It has an address, a manufacturer and a place in a room.

A component is what can be switched or read on that device. A Shelly 2PM is one device with four components: two switching outputs and two power measurements. A weather station can have a dozen components — temperature, wind, brightness, rain — all belonging to one device.

Where you notice it

• A room holds components, not devices. Assign a device to a room and its components go with it.
• In automations and scenes you pick a component, not the device: you switch the first output, not the Shelly.
• Remove a device and the controller asks what should happen to its components — they may be sitting in rooms, scenes and automations.
• A message like "Another component already addresses this device" is about exactly this level: two components want to use the same address.

Why the distinction helps

A device is something from a catalogue, a component something from the house. The resident says "turn on the hallway light" and means a component; which device is behind it does not concern them. The controller keeps the two apart so that you can replace a device without rewriting every automation.