What are the similarities between unitary and federalist forms of government?

Before discussing the similarity between a unitary form of government and a federal form of government, it is necessary to establish the definition of each.
In a unitary form of government, all governmental and political power is concentrated in the central government. The central government may choose to transfer certain powers to the lower levels of government and also retains the right to revoke these powers. Therefore, the lower levels of government have only the powers that the central government allows them to have.
In a federal form of government, the central and lower levels of government have functions and powers that are granted to them by the country’s governing document, such as a constitution, and, therefore, cannot be unilaterally revoked. In essence, the central and lower governments are each given powers which prevents one level from exercising complete power over the other.
Although the two forms of government have significant differences between them, one key similarity is that they both engage in the process of power allocation. Essentially, both systems acknowledge that certain powers and responsibilities are better handled by the central government while other should be managed by lower levels of government. Although the way in which power is allocated differs between the two systems, the understanding that there is a need to allocate power is present in both.
It should be noted, however, that any discussion of the similarities between unitary and federal forms of government must make allowances for the unavoidable variables that exist from country to country. The way that one country implements a certain form of government may be very different from the way that another country implements the same form of government. As such, there may be variations in the similarities found if comparing certain countries (the United States which has a federal system and France which has a unitary system) rather than the governmental system as a whole and in more general terms (unitary and federal).
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