How does the democratic government differ from the oligarchic government

Usually, we hear people say that "The United States of America (for example) is a republic and not a democracy." You ask; what is the difference? The word "republican" applies to the character of the nation-state.A monarchy, for example, is not a republic. Saudi Arabia is a monarchy. Russia is a republic. The government of a monarchy invested in the King. The King is empowered by God. The government of republic can take many forms such as elected representative democracy or single-party communist state. But a republic draws its authority from the people. Democracy is having the character of the people. A republic that is based on democratic principles draws its authority from the people. A republic can be democratic or dictatorial. North Korea is a republic. Its full name is "The Democratic People's Republic of Korea." Even dictators thrive to be seen as democratic, even when they are not. The "Islamic Republic of Iran" has dozens of supposedly democratic institutions and elections. Fundamentally though those choices are limited to the people by the theocratic nature of the government.Iran is actually a Theocracy where a state religion rules. It may be important to realize that this issue is not a question another countries that either is well schooled in Government in general and/or do not have two major political parties namedRepublicans and Democrats.