“难辨的”常见英文表达有 indistinguishable、hard to distinguish 或 difficult to discern，具体使用取决于语境：
indistinguishable：强调事物之间极其相似，难以区分，常作形容词。
例句：The twins are so alike that they are indistinguishable from each other.（这对双胞胎长得太像了，简直难以分辨。）
hard to distinguish：侧重于描述区分动作的困难，是动词短语。
例句：In the fog, it was hard to distinguish the road from the fields.（在雾中，很难分清道路和田野。）
difficult to discern：强调辨识的难度，也是动词短语。
例句：The fine details of the painting were difficult to discern from a distance.（从远处看，很难看清这幅画的细节。）