The phrase "different as night and day" is often used to describe stark differences between two things or individuals. In search of synonyms that convey the same meaning, one can use "polar opposites", "worlds apart", "chalk and cheese", or "oil and water". These terms highlight the extreme contrast between two things, making it evident that they are as dissimilar as two things can be. Other synonyms, such as "black and white", "apples and oranges", and "fire and ice" also convey a similar message of two things being categorically distinct. These alternative phrases or idioms can be used to describe distinct differences in diverse contexts, be it culture, personality, appearance, or lifestyle.