Different kinds of laws are passed at federal, state, and local levels.
The federal government is responsible for some types of laws, such as those pertaining to national defense, currency, interstate commerce, patents, and so forth. State and local governments may not pass these kinds of laws, nor may they pass laws that conflict with federal laws.
The state governments may pass laws that are not explicitly reserved by the federal government. State laws affect the citizens and property in that state only. State laws may not conflict with federal laws.