Those are two different shows, one has been a long running favorite, the other a different story and soundtrack that started up for the 50th celebration stuff in May.
Cinderella's Surprise Celebration debuted in 2001 for the 100 Years of Magic Celebration and stars Cinderella, Mickey and friends as they have a musical party and give the gifts of love, laughter, courage, and friendship. The villains, however, drop in and take over the celebration. The villains segment is probably the reason it is still a part of MNSSHP instead of Cinderellabration. There is also usually a meet-and-greet after the show. During the MNSSHP last year, I believe it was mosty Villains.
Cinderellabration debuted in 2005 for the Happiest Celebration on Earth. It's premise is the royal corronation of Cinderella. The royal family, Fairy Godmother, royal court, and many of the Disney Princesses and Princes are in attendance and there's plenty of pomp and circumstance concerning the royal festivities. There is no Mickey and friends and no villains in this show.