The main difference between rules and laws is the consequences associated with breaking them. While each is developed to invoke a sense of order, fair play, and safety, the weight of a law is much heavier than the weight of a rule.
Laws are like the legal version of rules. When you are a child, a parent sets rules to be followed. When you are in a society, the government sets laws to be followed. When a rule is broken, the consequences tend to be uncomfortable but mild in comparison to the breaking of a law.
Laws are enforced by a higher governmental office, usually the police and the prosecutor’s office. Laws are written in specific code so that they can be interpreted as needed. When you break a law there is legal action that follows, provided that you are caught.
Rules are more flexible and carry low end consequences. You can set up rules for games, rules for the home, even rules for fighting or being intimate with a partner. Rules are personal in nature, and they are often adjusted as the conditions and circumstances of the home change.
Laws must be passed through due process in order to take effect. A law starts off as a bill, and must go through a series of checks, balances, and votes in order to become a law. Rules are merely set and adjusted as the need arises, and should be followed out of respect for those setting the rules.
Rules help us learn to prepare for living in society. As youngsters, we tend to learn that there are rules about hitting, stealing, lying, and being wasteful.