I'm afraid Advent is wrong. Anakin does not have a better craft. She has made the mistake of assuming that because Anakin's craft is far faster in atmosphere it is far faster in space. This is not so. Yes, Anakin's craft is the faster one, but only by a small amount in space.
Vader's craft IS more advanced than Anakin's. His ship has fewer laser canons, but this is unimportant in a dogfight because a short burst from 2 OR 4 lasers canons will destroy Anakin's ship anyway. It's the same reason the A-wing, which is possibly the most dedicated dogfighter in all of SW has only two canons. Neither ship needs much firepower.
Vader's craft has better shields and armor. It's a simple byproduct of having a ship more than 20 years more advanced than your opponents.