Final answer:
The United States had a democratic system, while the Soviet Union had a single-party system after World War II.
Step-by-step explanation:
The correct answer is: The United States had a democratic system, and the Soviet Union had a single-party system. After World War II, the United States remained a democratic country with multiple political parties and a capitalistic economy. On the other hand, the Soviet Union adopted a single-party Communist system with a planned economy. These political and economic systems led to different social, cultural, and economic developments in the two countries.
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