Differentiation is how someone or something is set apart from others. If you make a differentiation between one brand of toothpaste and another, you point out how they're distinct.
You can see the word different in differentiation. The -tion ending tips you off that differentiation is the noun form of different: differentiation refers to the differences themselves. Suppose two very similar movies come out at the same time. The studios will work to achieve differentiation in the films' trailers, with one highlighting the chemistry between the romantic leads and the other showing moments of slap-stick comedy.
