another pair of shoes字面意思是另一双鞋，真实含义是另外一码事，另当别论，迥然不同的另外一回事。

【例句】
He can be as sharp as any man when it's a question of business; but duty's another pair of shoes.
他做起生意来跟别人一样精明，但是承担责任就是另外一码事了。

If you say he's your godfather, that's another pair of shoes. I suppose you can rely on him to help you.
你若说他是你的教父，那就另当别论了，我猜想你能领带他来帮助你。