What's the real difference between the Great Wall and a city wall?

Answer: Great Wall delays invaders; city walls actually stop them

Great Wall delays invaders; city walls actually stop them ✓ — Correct! The Great Wall is a 5,000+ km tripwire — mostly unmanned, designed to slow steppe raiders and signal the imperial center to mobilize cavalry. A city wall is a sealed perimeter with a full garrison, designed to physically stop attackers at the wall itself. Same word 'wall', completely different jobs.

Great Wall is taller and thicker than any city wall — Wrong. Most Ming Great Wall sections are about 7-8 m tall and 5-6 m wide — thinner and shorter than major city walls like Nanjing's (12-21 m tall, 10-20 m thick). The Great Wall's only superlative is length.

Great Wall protects emperors; city walls protect commoners — Wrong. Both walls protected ordinary people. The Great Wall guarded farming villages from steppe raids; city walls protected urban populations. The real divide is function (delay vs stop), not class.