The main difference between the opening in the new and old version is the story now starts with a description of a specific celebration dinner. In the original version, we were first told about Nancy's unhappiness with her family life.
There are a couple of events that have now been linked together.
In the new version, the damage to Della's mobile phone is caused by Nancy's lack of concentration - and she is not concentrating because she is still unhappy. Spilling the water is linked to the previous night's celebratory dinner and how that has made her feel about her life.
And the girl whose wallet was stolen now has a reason for accusing Nancy - the HK$2,000 Nancy owes Della has been repaid.
Also in the new version I've brought Nancy's mum to the school rather than Nancy's room. The idea is to create the maximum pressure on Nancy at the peak, or climax, of the story. So when her mother explains what she has done, and how she feels about her daughter, we feel even more relieved and happier.
Don't worry if you preferred the original version of the story. Remember, there's no right and wrong when it comes to the way you shape your stories. While some techniques and styles tend to work better in most stories, this won't be true all the time or for all writers.