Yes they can
It usually called the federal government and individual agencies are mostly called the United States __________. ( Department of .., Court of ... , Treasury, etc,) It is centered in Washington, DC.
union government.
National Government, Central government(as opposed to state)
I am assuming by level, you mean level of government. There is no distinction between government on a national level and government on a federal level. The federal level of government is the highest tier of government because its central to the nation. It represents a union of states. Those union of states form a nation. So you see how the two terms are interchangable, and can be used synonymously. The federal government is government on a NATIONAL level.
Federal
In the US, the Federal Government is referred to as both a National and Central government, which has shared and separate powers with the 50 States that belong to the US.
The national government is located in Washington dc
The power-sharing between a central government and those of the individual states is a federal government.
Federal
federal, national, and central
federal, national, and central
How has the American federal system solved the problem of how to maintain an efficient and effective central government and preserve national unity?