Why might obeying the law be a duty rather than a responsibility?

Obeying the law be a duty rather than a responsibility because:

A duty is also called an obligation and responsibility, as it is something that a citizen is required to do according to the law of the land. Some of the example of duties and obligations are obeying laws, paying taxes, defending the nation etc.

Though sometimes there are some responsibilities, which a Citizen is expected to perform, but are not required by law. For example responsibilities such as voting, attending civic meetings, petitioning the government and running for office or contest election for the good of the people.