The key scene in "The Good King Arthur" that shows a different detail than in "Excalibur" relates to Arthur's motivation for retrieving the sword. In "The Good King Arthur," Arthur is motivated by a desire to be of service to his brother, Sir Kay, who has forgotten his sword: "I will fetch it for you," cried the young Arthur, anxious to be of service.
In contrast, in "Excalibur," Arthur's motivation is characterized by a sudden sense of determination and wrath to provide his brother with a weapon for the tournament, indicated by his declaration: “From yonder mystic stone / I’ll pluck the sword, that good Sir Kay / May wield it as his own!”
This difference highlights that while both passages depict Arthur drawing the sword, the reasons for doing so are portrayed differently, showcasing Arthur’s selfless service in one version and a more assertive, competitive spirit in the other.