what is difference between volition and intention?

As per buddhism what is the difference between volition and intention? If there is any difference what is right pali word for volition and what is right pali word for intention? I presume sankhara is volition. and cetnā is intention. There are other word also that we should throw light. they are Chanda, and Sankappa, vaci sankhara. kaya sankhara. And If you answer is that they are same then. (1) the wastrn philosopher descriminates that. (2) Moreover There is volition in every feeling/phassa as said by buddha. When we do breath observation.**There is intention to observe breath and that is boosted time and again. But at the same time there is volition to scratch/move my body** or to suffer my bodily pain.. there must be different between this two volition. isn't it.? I guess one of the two(volition/intention) is conscious and **other is unconscious**!!