The fundamental difference between a Sudbury school and any other type of school is the student's level of responsibility. In a Sudbury school the students are solely responsible for their education, their learning methods, their evaluation and their environment.
In a public school, the state takes responsibility for most aspects of a student's education including curriculum and evaluation. The student is left with little responsibility except to learn what is taught, how it is taught, in the environment in which it is taught and then to reiterate it back at evaluation time.