A mill is a device that breaks solid materials into smaller pieces by grinding, crushing, or cutting. After the grinding the state of the solid is changed: the grain size, the grain size disposition and the grain shape

A sieve is a device for separating wanted elements from unwanted material or for characterizing the particle size distribution of a sample, typically using a woven screen such as a mesh or net or metal. Sieving is a simple technique for separating particles of different sizes.