The phrase "tell apart" means to distinguish or recognize the difference between two or more things. Some of its antonyms include confuse, mix up or blur, which suggests an inability or difficulty in telling things apart. Another antonym for "tell apart" is classify, which implies arranging things into groups based on their differences. Additionally, words such as identify, spot, and differentiate can be considered antonyms of "tell apart" as they suggest the ability to recognize and distinguish one thing from another accurately. In contrast, other synonyms such as equate, unite, combine or merge serve as antonyms by suggesting a lack of differentiation, blurring distinct boundaries and failing to tell things apart.