Dear student, 1. when a body covers equal distance in equal interval of time ,however small may be the interval be body is said to be in uniform motion.The graph between the distance covered and the time is in a straight line. 2.when a body covers unequal distance in equal interval of time ,however small may be the interval be body is said to be in non-uniform motion.The graph between the distance covered and the time is not in a straight line.Regards.