I think it’s more about intent and what you do with the findings. If you and your team announce your plans ahead of time, document everything meticulously, deliver the pieces to a museum or archive, publish papers and delivery seminars and attend conferences on it… it’s probably archaeology.

If you and your associates do it all in secret, sell the artifacts to some rich asshole (esp. via a fence), and cover your tracks, that seems a lot more like grave robbing.