The Chinese idiom 截然不同 is formed through a vivid metaphorical structure: the first two characters, 截然 (jiérán), literally mean "sharply cut off" or "severed", evoking the image of slicing something cleanly into two separate parts. This is combined with 不同 (bù tóng), which means "not the same" or "different". Together, the phrase creates a powerful analogy, suggesting that two things are as distinctly separated and unlike each other as if divided by a sharp cut, thereby emphasizing a complete and absolute difference rather than a minor or gradual one.