Many people often confuse stretch wrap, also called stretch film, with shrink wrap; thinking that they are the same, when in fact they are completely different products / processes.
Stretch Wrap is usually a clear plastic film that is wrapped tightly around a group of items numerous times to stabilize and unitize it. As the film is wrapped, it is stretched and clings to itself, much like kitchen saran wrap, to form a tight package. It can be applied either by hand, semi-automatic or automatic stretch wrapping equipment. See below video demonstration.
Shrink wrap on the other hand, while also a clear plastic film, is usually used to package a single item. The item is placed in between two layers of film; the film is then cut and heat sealed around the product. With shrink wrapping, the film actually shrinks around the product to form a tight package protecting it from the environment.
In short, stretch wrap uses tension and cling to unitize, where as shrink wrap uses heat.
I hope this helps clear up the confusion between the two processes, so you can choose the right solution for your needs.