All Barbour tartans originate from the same "sett", - that is sharing the same pattern and weight of lines- and have been confirmed by experts Kinloch Anderson based in Edinburgh. In historical precedent, Barbour changed the linings according to requirements and they continue to bring in tartans for specific needs.
In broad terms, Navy garments take the Dress Tartan, Sage garments take Ancient Tartan (Green/Cream), Black garments use Modern Tartan (Grey/Black), Rustic garments take Muted Tartan (Brown/Cream) and the Olive or Classic garments take the Classic Tartan. (pictured in this order)