Machining is a big-small approach where a big block becomes a small product, while AM is a small-big approach where small blocks become a big product. These are two different approaches. This brings up a question of whether these two approaches are still different if observed through the movement of tools. Machining can be a top-down approach, while AM can be a bottom-up approach—these approaches can be due to the direction of the tool movement—the tool moves from top to down in machining while from bottom to up in AM.