How does a communist party differ from a democracy. These are not answers to homework.?

I am trying to write an essay. And I first wanna come up with the facts so that the paper will turn out even better. So if you have anything to add on the differences between the two parties that would help dramatically. The topic of the paper is: How America different from other countries. So anything else that you add that would fit within the topic would help me severly. Thanks Alot!!! I know ill go great.