When games are made, usually there is a version for each country it
is released in. Nintendo sometimes changes the smallest things, something
simple like text. Or sometimes they actually go as far as changing
the whole game, when in the end the only thing alike between them
is the title.
The same goes for Kirby games. However, Kirby hasn't
been changed as much compared to some other series. Here is some information
in comparing as many different versions of the games available.