Final answer:
Umbrella departments oversee a broad range of functions, unlike single-issue departments. The Department of Homeland Security was created to centralize and coordinate various federal agencies following 9/11. It has a hierarchical structure with various levels to handle different specialties within its scope.
Step-by-step explanation:
Umbrella departments such as the Department of Homeland Security are major executive offices designed to oversee a broad range of functions and agencies that may have previously operated independently. In contrast, single-issue departments focus on specific policy areas or concerns. The formation of the Department of Homeland Security was a response to the realization that there was a lack of coordination among various federal agencies, which was highlighted by the 9/11 attacks and later by the inadequate response of FEMA after Hurricane Katrina.
Each cabinet department, including the Department of Homeland Security, has a hierarchical structure with many levels, such as secretaries, undersecretaries, and bureaus, to handle different aspects and specialties within their scope. The heads of these departments report directly to the President and are responsible for large bureaucratic networks that aim to fulfill the department's mission-oriented functions. Laws such as the National Security Act, the Patriot Act, and the Homeland Security Act have significant impacts on how these departments operate, particularly concerning foreign policy and domestic security concerns.