What are the similarities and differences between a monarchy and a dictatorship?

Dictatorships are systems of government in which you have only one ruler. Such a ruler has supreme power and dictates all laws. The country is run on the will of the dictator and his power cannot be challenged. Usually there are no elections. A dictator normally gains power either by overthrowing a previous regime, when an elected head of government refuses to vacate his/her position, or when control is passed on from a previous dictator to a new leader who can be either a relative or a close associate. The regime in Iraq under the leadership of Saddam Hussein was an example of a dictatorship, as was that of Italy under Benito Mussolini. Dictatorships generally end when there is a violent overthrow of government.

A monarchy, in general terms, is similar to a dictatorship in that the country is ruled by a king or a queen. In monarchies though there are different levels of control. An absolute monarchy is most similar to a dictatorship. The king, queen, or emperor has absolute power that cannot be challenged. As in a dictatorship, there are no elections. Saudi Arabia is a good example of this type of monarchy. The Saudi king dictates laws and policy. 

In a limited monarchy, such as in England, the king or queen only has ceremonial powers and no real authority. In a constitutional monarchy, the king, queen, or emperor has only certain powers as prescribed by the constitution. Sweden has such a monarchy. In monarchies, the monarch's authority is passed on by birth and power is retained within the family--this is generally seen as a divine right.

Because so much power is vested in the hands of a single person in absolute monarchies and dictatorships, many abuses of power result. Such leaders generally oppress their subjects either to retain authority or to enrich themselves and their closest supporters or relatives. It seldom happens that such leaders put their citizens first and act in their countries' best interests. The end result is, more often than not, rebellion and an overthrow of the regime.