Congressional Record is the proceedings of the United States Congress. There were several preceeding titles: The Debates and Proceedings in the Congress of the United States [1789-1824]; Register of Debates in Congress [1824-1837]; and The Congressional Globe [1833-1873]. Also online are the Journals of the Continental Congress, 1774-1789.
Congressional Reports eventually become part of the U.S. Congressional Serial Set. Congressional Reports, consisting of Senate and House Reports, are important for several reasons: 1) they often present the legislative intent of congressional bills (why was this law needed?; what were the legislators thinking?; and 2) they often present statistics and other useful background information.
Like Congressional Reports, Congressional Documents eventually become part of the Congressional Serial Set. They are not usually deemed as important as Reports in recent years are very often the signing statement of the President. Other Documents can be research and reference works, such as the Biographical Directory of the United States Congress.
Hearings are less important to legal researchers, but more important to social scientists. A hearing is a published version of testimony spoked before congressional committees, as well as materials submitted to the committee.
Recent years of the Serial Set contain only congressional Reports and Documents. However, in earlier years other congressional and executive branch materials were incorporated into the Serial Set. This included annual reports of executive agencies and statistical compilations. The Serial Set was not published until 1837, covering the years 1817 onward. After that a retrospective series was deemed necessary to incorporate federal materials from the time of the earliest days. This series in known as the American State Papers and covers 1789-1838.
Public laws are also known as "slip laws" because of their initial publication in individual slip format. They are eventually bound together into the United States Statutes at Large, a sequential publication of laws in the order they were signed into law.
The statutes are the law "as passed", but the compilations are the codification of the law into the United States Code, the law "as amended." The US Code is divided into 50 titles (not all of which are currently in use).
Three congressional entities provide reports on the outcomes of legislation. These are the CRS (Congressional Research Service, an arm of the Library of Congress), the GAO (Government Accountability Office, formerly known as the General Accounting Office), and the CBO (Congressional Budget Office).