Key Difference: An act is an official copy of a statute or regulation that is initially presented in the form of a bill and after being verified it is passed in the process of a legislature. An act is enforced in a legal manner. In context to an act, rules define the guidelines that must be followed for the successful implementation of the act.

Both the words can often create confusion as they both are widely used in context to laws. Therefore, it is important to understand the differences between the two.

An act can be described as a legal document or a statute that is passed by a legislator. It passes through various stages of review and approval in the Legislative Assembly. It contains certain regulations that are identified as important for the society. It can be a product of a decision or determination of a sovereign, a legislative council, or a court of justice. Acts, if passed, are then turned into laws. Thus, it refers to a document that is used to record a fact, something said or done.

A bill is the draft of a legislative proposal, which passes through various stages in order to become an act. It can be viewed as one of the sources of law. The acts are used for the creation of new laws or changing an existing law. The process of an act to become a law may vary from one country to the other.

On the other hand, rules are simple guidelines that are provided for the smooth functioning of an organization and to maintain a healthy environment among its people. Dictionary.com defines ‘rule’ as:

• A principle or regulation governing conduct, action, procedure, arrangement
• The customary or normal circumstance, occurrence, manner, practice, quality, etc.
• To control or direct; exercise dominating power, authority, or influence over; govern.
• To decide or declare judicially or authoritatively
• To make a formal decision or ruling, as on a point at law.

Rules can be enforced at any level. For example, a teacher might form a rule stating that every student in her class needs to show her homework everyday. The rules of these types are not rigid and depends upon the enforcing entity that how strict it is and what steps it has taken to ensure the proper implementation of the rules.

Therefore, we can say that acts are laws, but they are the ones that are formed after passing from the legislator, whereas rule defines the procedures of performing a task. The acts generally contain rules. For example, The Environmental Management Act of Netherlands contains rules on levies, contributions and compensation. Another example: under the Securities Act of 1933 of U.S., according to rules 505 and 506 of Regulation D, a company may sell its securities to the "accredited investors."

Thus, we can say that when we compare them in context to laws, then an act is the law that is passed by a process of legislature. On the other hand, rules are guidelines that are defined in the acts that must be followed for the enforcement of the act. In general, a rule can be described as a guide for conduct or an action. 

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