what is basic difference between speed and velocity graph?

Any object that is changing its speed or direction is accelerating. Speeding up, slowing down and going round a corner at constant speed are all examples of acceleration. Acceleration is a measure of how quickly the velocity of an object changes. Instantaneous acceleration = rate of change of velocity. It is represented by the gradient of a velocity–time graph. average acceleration = change in velocity ÷ time a = ?v ÷ ?t Acceleration is a vector quantity and is measured in m s–2. In physics, any change in velocity is an acceleration. This means that an object moving at constant speed, but changing direction, is accelerating. Speed–time and velocity–time graphs both give information about the motion of an object that is accelerating. The graphs below both represent the motion of a ball after it has been thrown vertically upwards with an initial speed of m s–1. read less

In Speed - time graph , the speed of a moving object can be calculated if the distance travelled and the time taken are known. The faster an object moves, the steeper is the line representing it on a distance-time graph. In velocity - time graph The velocity of an object is its speed in a particular direction. In velocity-time graphs sloping lines represent steadily increasing or decreasing velocities. Horizontal lines represent movement at constant velocities. read less