The government is responsible for making sure that there are different decisions that will be done in order to improve what is being governed as a whole. For example, if there are some states that would need to be disciplined, there are certain laws that will be set in place by the government to ensure that people have something to follow.
When you say governance, you are referring to the various rules, the norms, the structures, and so much more that should be followed to ensure that people will be properly regulated and will be held accountable for their different actions. Take note that there is such a thing as good governance and bad governance. The better the governance, the better that people will react.
Power and government are interchangeable regarding the process of governing, but they differ in other ways. The government often refers to the act of governing. Members of a government are engaged in governance. The government is a group of people who rule or run the administration of the country.
The government is the portion of representatives who govern and control the state at a specific time. The government is a channel in which the power of the state is active. Governance is the act of leading or ruling.
It is the set of guidelines and laws outlined by the government to be executed by the representatives of the state. Governance is a perception that can be followed in an organization of any time. Management is what governments practice daily.