Fixed casters, also called rigid casters or fixed wheels, are designed to move in straight lines without the ability to turn or swivel. They are commonly used for transporting heavy loads in a single direction where steering is unnecessary. In contrast, swivel casters have a raceway that allows the wheel to rotate 360 degrees, enabling easy maneuverability and changes in direction. Swivel casters are ideal for applications that require easy steering and navigation. The choice between fixed and swivel casters depends on the specific requirements of the task, such as the need for straight-line movement or maneuverability.