Final answer:
In a direct democracy, citizens directly participate in decision-making, while in a representative democracy, they elect officials to make decisions for them. The United States uses the representative model and emphasizes the protection of minority rights.
Step-by-step explanation:
The main difference between a direct democracy and a representative democracy (or a republic) lies in how laws and decisions are made by the citizens. In a direct democracy, people have the power to make governmental decisions directly, similar to the ancient Athenian assembly where male citizens could vote on all laws. By contrast, in a representative democracy, citizens elect officials, such as members of Congress or a president, who then make decisions and laws on their behalf. This is the system used in the United States, where it's also crucial for these elected officials to protect the rights of minorities against the majority, distinguishing a republic from a pure democracy.