This document compares and contrasts idioms and collocations. It notes that idioms, unlike collocations, allow no variation in form and their meanings cannot be understood from the literal definitions of the individual words. Idioms must be treated as single units. Collocations, on the other hand, are flexible patterns that allow some variation and are specific to individual languages. The document provides examples of idioms like "to get the wind up" and collocations like "quick shower" to illustrate the differences. It also discusses implications for translation, such as considering the degree of predictability or markedness of collocations.