“难以区别的”可以用英语表达为 “hard to distinguish”、“difficult to tell apart” 或 “indistinguishable”（形容词形式）。以下为具体说明：
1、 hard to distinguish
* 含义：难以区分、难以辨别。
* 例句：The two paintings are so similar that they are hard to distinguish.（这两幅画如此相似，以至于难以区分。）
2、 difficult to tell apart
* 含义：难以分辨、难以区分。
* 例句：The twins look so much alike that it's difficult to tell them apart.（这对双胞胎长得太像了，很难分辨。）
3、 indistinguishable（形容词）
* 含义：难以区别的、无法分辨的。
* 例句：The two samples were indistinguishable under the microscope.（在显微镜下，这两个样本难以区别。）