what is the principle difference between autocracy and oligarchy
Autocracy comes from the classical Greek words autos (self) and kratos (strength). It signifies government by an individual with supreme power, without input from the people. Oligarchy is from Greek oligos (few) and archein (to rule).
The autocracy form of government is characterized by the presence of a single leader who rules the people. It is akin to the dictatorship form of government. Oligarchy power of government rests in the hands of only a few people as opposed to autocracy where the power rests in the hands of a single person. Doug Friedman.