Released to commemorate the 40th anniversary of the Donkey Kong franchise, this NES version of Donkey Kong Jr. likely features updated graphics and sounds, possibly incorporating elements of nostalgia or even gameplay additions. Specific details would depend on its content, but it is clearly aimed at celebrating the legacy of the franchise.  Presumably, Nintendo, as the rights holder, played a key role in developing and releasing this special edition to appeal to long-time fans.

Donkey Kong Jr. 40th Anniversary

Donkey Kong Jr. (Japan) (Disk Writer)