The surgeon transplanted a liver into the boy. と The surgeon transplanted a liver to the boy. はどう違いますか？説明が難しい場合は、例文を教えて下さい。

Because a liver lives inside a human body, the sentence "The surgeon transplanted a liver INTO the boy," makes sense.

"to the boy," does not make sense because the surgeon did not give the liver to the boy. He must put it inside the boy's body, it is not a present.