Dear Student,
The powers are shared among the 3 organs of the government based on their functions:
The primary role of the legislature is to make new laws that become necessary to govern a country or a state. Another important role of the legislature is to approve the budget for a government. Governments need to seek approval from the legislature to raise new taxes and to spend the revenues obtained from taxation. In Parliamentary democracies like India, legislatures also have the important role of overseeing the functioning of the Executive. Ministers need to be members of the legislature and they are answerable to the legislature for their activities. The executive has to implement whatever has been legislated. Judiciary makes sure that legislature and executive follow their duties.
Regards