In addition to confusingly using the "Adventure Island" brand for the Japanese release, this version was released in the territory before any version of the original Monster World II, due to some unfortunate circumstances. It should be noted that the Adventure Island series is known in Japan as "冒険島" spelled in Japanese, compared to the English spelling of this game. On the other hand, this version was released before Monster World III, so technically Japan got the games in order.
Because of the hardware jump, Adventure Island is a big improvement over the original Monster World II. The relationship is very similar to the two versions of Monster World III, but in reverse.
Both the TurboGrafX-16's Dragon's Curse and Wonder Boy III: The Dragon's Trap have been released on the Wii's Virtual Console service, despite being roughly the same game. Similar situations have occurred with Wonder Boy III: Monster Lair and The Dynastic Hero.