VolumeCamera And Main Camera

Hello everyone,
What are the differences between unbounded Volume Camera and Main Camera of XR Origin?
How will unbounded Volume Camera’s position and rotation affect the Main Camera?

Afaik, volume camera is used by RealityKit. It is used for rendering.
You can use Main Camera for getting position and rotation of the device.
I guess the both cameras have the same position and rotation.

Is there a way to use the user’s position main camera to move the volume?