What is the difference between wagon and trailer?

A wagon is typically a self-contained vehicle, often with wheels and drawn by animals or a motorized vehicle, used for transporting goods or people. In contrast, a trailer is a non-motorized vehicle designed to be towed by another vehicle, like a car or truck, and it usually does not have its own means of propulsion. While both are used for transportation, wagons are often standalone units, whereas trailers rely on another vehicle for movement.