We can say 'a different kettle of fish'.

我们可以说“截然不同的事”。

“Honey Money”, Catherine Hakim's provocative book, is a different kettle of fish.

凯瑟琳? 哈金挑起争议的著作《甜蜜的金钱》则有截然不同的观点。

I found French an easy language to learn, but Japanese was a different kettle of fish.

我发现法语很容易学，但日语就不一样了。

When one situation is very different from another, we say it's a different kettle of fish.

当一种情况与另一种情况非常不同时，我们就说这截然不同。

American English sounds nice and it's easy to understand, but British English is a different kettle of fish.

美式英语听起来很不错，而且也容易理解，但英式英语就完全是另一回事了。

She enjoys public speaking, but being on TV is a different kettle of fish.

【kettle】她喜欢当众演讲，但上电视就完全是另一回事了。