Government Corporations. Government corporations do not belong to any department — they stand on their own. Probably the best-known government corporations are the United States Postal Service and Amtrak. They are different from other agencies in that they are businesses created by Congress, and they charge fees for their services.
Independent agencies can be distinguished from the federal executive departments and other executive agencies by their structural and functional characteristics. Congress can also designate certain agencies explicitly as "independent" in the governing statute, but the functional differences have more legal significance.
Independent Agencies. Independent agencies closely resemble Cabinet departments, but they are smaller and less complex. Generally, they have narrower areas of responsibility than do Cabinet departments. Most of these agencies are not free from presidential control and are independent only in the sense that they are not part of a department.