Difference between act and rule utilitarianism?

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Act utilitarianism is the belief that an action becomes morally right when it produces the greatest good for the greatest number of people, while Rule utilitarianism is the belief that the moral correctness of an action depends on the correctness of the rules that allows it to achieve the greatest good."

1. Act utilitarianism is the belief that an action becomes morally right when it produces the greatest good for the greatest number of people, while Rule utilitarianism is the belief that the moral correctness of an action depends on the correctness of the rules that allows it to achieve the greatest good.