The difference between speed and velocity lies primarily in the inclusion of direction. Speed is a scalar quantity, representing how fast an object is moving without regard to its direction (e.g., 60 km/h). In contrast, velocity is a vector quantity that includes both the speed and the direction of the object (e.g., 60 km/h north). Understanding this distinction is essential in fields such as physics, where the direction of motion affects outcomes in various equations and principles.