When dealing with these two topics which are very similar we are dealing with angular motion, or motion in a circular direction. To explain these i will use the example on a ball moving within a ring of some radius. As teh ball goes around the ring at a constant velocity there are many forces acting on it. The one we are concerned about is the force the ring exerts on the ball, causing an acceleration (change in direction). The acceleration caused by this force is called the centripital acceleration, sometimes mistakenly called the centripital force.

Now imagine you are in a car traveling at a constant speed. You then make a short turn. You feel a force pushing you towards the side of the car away from the center. This is an imaginary force called the centriphical force. What this really is, is your inertia wanting you to continue in a straight line of motion.