NSURLVolumeIsInternalKey vs NSURLVolumeIsLocalKey

Can someone explain the distinction between these two attributes: NSURLVolumeIsLocalKey and NSURLVolumeIsInternalKey?

The documentation for NSURLVolumeIsLocalKey:

Key for determining whether the volume is stored on a local device, returned as a Boolean

NSNumber

And the documentation for NSURLVolumeIsInternalKey:

Key for determining whether the volume is connected to an internal bus, returned as a Boolean

NSNumber

nil

So, when I look at the values of these attributes for a volume mount on the local network both are NO as expected.

When I connect a usb stick to my Macbook pro via a dongle (since i only have USB-c ports) I get YES for local, but NO for internal when I was actually expecting the values to be the other way around. Can someone clarify the distinction between these two attributes?

Thanks