Antonyms for the term "just noticeable differences" can be broadly categorized into two groups - similarities and sameness. Words such as uniformity, conformity, likeness, constancy signify similarity, indicating that there is no perceivable difference at all. On the other hand, words like substantiality, enormity, significant, substantial signify sameness, implying that the difference is very noticeable and impactful. These antonyms indicate a lack of variance, diversity, and novelty, which can be seen as either desirable or undesirable depending on the context. In conclusion, antonyms for the term "just noticeable differences" provide a rich variety of vocabulary to describe the opposite of a minimal but significant change.