It has been over a decade since the original launched, so it's understandable Nintendo would touch-up specific areas and introduce new features in Kirby's Return to Dream Land Deluxe for a more modern audience.
In fact, Deluxe toes the line as a pseudo-remake of its predecessor.
New copy abilities, such as the Mecha and Sand forms, debut for the first time in Deluxe, growing Kirby's capabilities further.
There are also more than 20 returning copy abilities from across the franchise, including Festival featured in Kirby Star Allies, as noted on the Nintendo store page.
Older abilities like Hammer and Stone received updates to feel like their renditions in recent Kirby games. And, of course, since there are more abilities, you can encounter new enemies and mini-bosses throughout multiple levels.
Kirby's companions Meta Knight, King Dedede, and Bandana Waddle Dee also have updated move lists from Kirby Star Allies in Deluxe. And in co-op mode, you and your friends can choose to play as different colors of Kirby from start to finish, unlike the original, which forces everyone to play as different characters.
Additionally, you can enjoy new challenge stages added to the Lor Starcutter alongside a revamped collection of mini-games found within Merry Magoland, an amusement park created as a separate mode in Deluxe.
Nintendo has basically overhauled the original game with new flourishes and added content to keep players locked in longer. Surprisingly, the developer even included a Magolor Epilogue story to the game.