It's easy for you to say that, but actually it is not so simple.

你说得倒容易，事情哪有那么简单！

《新英汉大辞典》

This is actually not the case. It's not as simple as that.

事实并非如此，没那么简单。

youdao

This is actually not the case. It's not as simple as that.

事实并非如此，没那么简单。

youdao