Students who excel having the direct attention of a teacher should sign up for a private class. Since you will be the only student, curriculum and learning pace is personalized for you. Classes will be intense, maximizing individual progress.
On the other hand, some students prefer a group class. This is a great way for friends or siblings to take an instrument together. If you thrive on peer learning, this is the class for you. Lessons will be conducted at a comfortable pace, since all students will be learning the same curriculum together.