The main difference between hot melt adhesive blocks, strips, and pillows lies in their physical form and how they are used. Hot melt adhesive blocks are solid chunks of adhesive that require melting in specialized equipment. Hot melt adhesive strips come in a pre-formed strip format and are used in manual or semi-automatic application processes. Hot melt adhesive pillows are pre-formed adhesive units enclosed in a casing and are employed with specific applicators or dispensing systems. The choice of form depends on the specific application requirements, adhesive volume needed, and the equipment available for melting and dispensing the adhesive.