Your path through the ball gives you the curvature of the ball. Swinging from the inside to the outside helps you draw the ball. Swinging outside to inside (aka cutting across the ball, or what usually happens when you come over the top) makes you slice the ball. Your clubface at impact determines the initial direction of the ball. For a right-handed golfer, open clubface at impact = ball starts right of target. Closed clubface at impact = ball starts left of target.