https://www.norsepower.com/technology
An excerpt:
The Norsepower Rotor Sail technology is around ten times more efficient than a conventional sail, because more lift is produced with a much smaller sail area. Due to its simplicity, it requires no reefing or crew attention when in operation. It is “push-button wind propulsion” from the bridge.
An image:
We see that the rotor is well maintained, leading to a smooth and fast rotation. For an AWES, such a holding is more difficult if even possible, excepted with a heavier building. So a lower efficiency or/and a higher power consumption can be expected.