The nineteenth trump changed composition between the older and newer patterns, and the change is easy to miss because both versions are cheerful.
The French pattern shows two children beneath a large sun, standing beside or in front of a low wall. Readings of the pair vary, twins, companions, two aspects of one person, a scene of children playing, and the wall is unexplained. The Rider-Waite-Smith card replaces them with a single child riding a horse beneath a banner, in front of a wall of sunflowers. The 1909 version is more triumphal; the older one is more domestic, and arguably stranger, because two small figures in an enclosure under an enormous sun is not obviously a picture of victory.
The Sun is one of three consecutive celestial cards, Star, Moon, Sun, and their grouping is stable across nearly all early orderings, which is one of the better arguments that the trump sequence was designed with some structure rather than assembled at random. What that structure meant is not recorded.
The Golden Dawn assigned the card the letter Resh, the Sun itself, and the thirtieth path from Hod to Yesod. Resh means a head, and the order read the card as consciousness fully illuminated. It is among the least controversial attributions in the system, for the obvious reason that a card called the Sun assigned to the Sun does not require much argument.
The wall is the detail worth sitting with. It appears in both the older and the newer versions, and in neither is it explained. Whatever the card promises, something in the picture is enclosed, and readers who notice it tend to get more out of the card than readers who take it as unqualified good news.