Why does the exact balance of power between the centre and the state governments vary from one federation to another?Explain with two examples.

The exact balance of power between the Centre & State Governments varies from one federation to another because this balance depends mainly on the historical context in which the federation is formed.
The two kinds of routes through which federation are formed are as follows:-
i.) ‘Coming together ’ federations:- States come together on their own to from a bigger unit or federation by pooling sovereignty. They retain their identity. Such federations are found in the US, Switzerland and Australia. In Such federation, constituent states usually have equal power and are strong vis -a- vis the federal government.
ii.) “Holding together ”federations:- In this type of federation , a large country decides to divide its power between the constituent states and the national government. The examples are India, Spain and Belgium. In such federations, the central government or the national government is more powerful than states government. At times, some units are given special
powers or status as in case of Jammu & Kashmir in India.