Things that show a difference or act in different ways can be described as differential. You and your sister may get differential benefits from eating a vegetarian diet.
You're most likely to come across the adjective differential in scholarly or scientific writing — it's really just a more formal way to say "different" or "differing." Sociological studies or articles often describe differential circumstances or outcomes, like the differential effects on various children of being raised with one parent. The Latin differentia is at the root of differential — it means "diversity or difference," and it comes from differre, "to set apart."