"细微的区别及差异" can be translated into English as "subtle distinctions and differences" or "nuanced differences and distinctions".
Both expressions convey the idea of small, often not immediately obvious, variations or contrasts. Here are some examples of usage:
There are subtle distinctions and differences between the two products that you might not notice at first glance.
The artist captured the nuanced differences and distinctions in the facial expressions of his subjects with great skill.