In the United States there are three levels of government: national, state, and local. Each level of government has its own responsibilities.
All the levels of government have three branches. That’s one way they are the same. The three branches are the legislative branch, the executive branch, and the judicial branch. The legislative branch makes the laws. The executive branch makes sure the laws are followed. The judicial branch settles legal conflicts. The judicial branch is made up of courts. The courts apply, explain, and interpret the laws that the legislative branch makes.
A state government is responsible for things that happen only in that state. Each state has a department of transportation that is responsible for building and maintaining state roads. Each state issues marriage certificates, birth certificates, and driver's licences. Each state licences teachers, lawyers, and doctors. These licences give them permission to teach, practice law, and practice medicine in that state.