Federal statutes are the laws enacted by the federal legislative branch, the United States Congress. Federal regulations are issued by the various federal administrative agencies, which get their authority to regulate from specific statutes. Regulations are designed to implement and interpret statutes. Both federal statutes and regulations are considered sources of binding authority on all individuals and entities in the United States.
As a general rule, it is best to begin your research with the relevant statute(s) and then move on to the related regulation(s) because statutes provide the basis for regulations. Also, statutes tend to be cited more than regulations and therefore, are usually easier to find. Once you find a relevant statute, it will typically lead you to the related regulation(s).
Federal statutes and regulations can be found in codes. The code is usually the best place to look up a statute or regulation because it is organized by subject and updated on a fairly regular basis.