To differentiate means to recognize or show the differences between two or more things. When you differentiate between a frog and a toad, you notice that frogs have smooth, moist skin while toads have dry, bumpy skin. When a teacher asks you to differentiate fact from opinion in a news article, you're separating statements that can be proven true from someone's personal beliefs.

In everyday use, it simply means noticing what makes things distinct from each other. A biologist might differentiate between similar species of birds by studying their beaks and songs. You might differentiate between identical twins by noticing one has a slightly different laugh or walking style.

Scientists and researchers often need to differentiate carefully, like when medical researchers must differentiate between symptoms of different diseases to make correct diagnoses. The ability to differentiate improves with practice and attention: the more you learn about something, the better you become at spotting the subtle differences that matter. A beginning musician might struggle to differentiate between a clarinet and an oboe, while an experienced conductor hears the difference immediately.