Individual Rewards: Individual rewards can be given to students who are doing good on an assignment, listening, and being a good role model. In some classrooms they use raffle tickets or "money" that is kept, saved, and spent on what the student decides to use it towards. These rewards include line leader, no homework, eating lunch with the teacher, etc. Teachers can use a multitude of different strategies for their students to gain individual rewards. This is a great way for acknowledging students' own achievements in the classroom.
Classroom Rewards: Classroom rewards can be earned through many different ways. The difference is that the reward is aimed for the whole class. Such as watching a movie, or extra recess time. A way a teacher can do this, is by keeping a jar for the whole classroom, and everytime the teacher notices the class is doing well emotionally and academically they place an item into a jar. When the jar is full, the class collaborates on the reward they would all like to do to celebrate.
All in all, it comes down to the teacher's incentive on how they see best to reward the class as each student is different.