gmail – How to filter and label messages like "INTERNAL-ONLY" and "EXTERNAL"

I would like to create a pair of labels.

The one would be "INTERN ONLY". This label must correspond to mail threads that include only the senders and recipients on the thread whose mail domain, @, matches my domain.

The second would be "EXTERNAL". This label must match the disjointed set. These are threads that contain no matter who in the list of senders or recipients whose mail domain is other than @