Capitalism- An economic and political system where a country's trade and industry are controlled by private owners for profit, rather than by the state.
A similarity that oligarchy and democracy have is that only certain people have control over power in each. A difference is that democracy is controlled by members. Oligarchy is only in a few people in dominant classes.
A similarity that monarchy and autocracy have in common is that only one person have power in both of them. A difference between them is that autocracy only have power over others, monarchy has supreme power, as in over multiple things.