In compulsory gymnastics every child in the same level does the exact same routine, and in optional gymnastics they do different routines. In optional gymnastics there are a set of guidelines, or level requirements and routines are built around them. Each gymnast has her own music (on the Floor Exercise) and choreography. Her routine is built to show off her strengths.
Scores are based on how well she performs the skills in the routine, whether she has all the requirements and whether the overall routine is enjoyable to watch.