The Federal Constitution is the Supreme Law of the Land. Legislation is the law passed by Congress. Regulations , derived from government agencies, administer the legislation by spelling out procedures and specifications. For example, the law says food packages must list ingredients. Regulations would specify that ingredients must be in English and in legible print.
Court cases force the courts to interpret the meaning of laws and regulations.
Public laws are organized into 50 sections or titles so that all related public laws are grouped together. Included are annotations referring to decisions of federal and state courts and law review articles. Law review articles do NOT have the weight of law, but suggest ways the courts might interpret the law. Subject index volumes are available. A series of supplements presents forms, regulations, etc.