"A review of food vocabulary and the differences between healthy and unhealthy food" = Is much better grammatically, but your sentence is unclear as to what you are trying to say. Is it looking at the vocabulary used in selling fast foods compared with healthy foods? You will get better help if you tell us what the sentence is to be used for.

Is it some kind of order sentence? Is "review" a noun or a verb in your sentence? Anyway, " the difference" instead of "differentiation".