It's a simple to use app created for teachers and students to provide teachers environment to test students.
Teacher type of an account allows to create quizzes, deleting own quizzes and also to check on students results. To create that kind of account you have to own special code that you have to use while signing in.
Has less features than teacher type. In register form you have to pick your class and school in order to see quizzes that teacher prepared for your class. Student account is created generally to take part in quizes.