Of course, sight is different from vision. Generally speaking, sight is the ability to interpret information and surroundings from the effects of visible light reaching the eye. We also call it as eyesight. On the other hand, vision which has the visual system, enables organisms to process visual detail, as well as some non-image forming functions. We can say that vision can interpret information from visible light to build a representation of the surrounding world. In other words, sight is the process of the eyes to focus an image on the retina; and vision is the ability of the brain to give this image meaning. Anyway, if you still have some question about them, you can just ask your eye doctor.