Radial motion blur creates a blur that radiates outward from a central point. It gives the impression of motion away from or toward the center of the image. Use it to convey a sense of rapid movement, explosion, or a centrifugal force effect.
Linear motion blur creates a blur that follows a linear path, typically in a single direction. It gives the impression of movement along a specific trajectory. Use it to convey the movement of an object in a straight line, such as a car on a road, a person walking, or a moving train.