The word 不同 is formed by directly combining two independent characters: 不 (bù), which functions as a negator meaning "not", and 同 (tóng), which means "same" or "identical". Their combination is a straightforward, logical construction where the meaning of the first character negates the meaning of the second, resulting in the core concept of "not the same" or "different". This is a classic example of a Chinese compound word where the unified meaning is derived transparently from the sum of its parts.