1. To make something, or someone, not like others of the same kind: The color of their eyes is one thing that differentiates Mary's twins from each other.

There is little to differentiate one dictionary from another one because they all tend to have the same or very similar definitions and too often lack clarity because they use another form of the word that is being presented.

2. To identify that which sets one thing apart from something else; to tell one thing apart from another based on characteristics: For some people, including Janet and Linda, it is not easy to differentiate between ice cream and frozen yogurt.