Imprint and stenciling are 2 different methods. Imprint uses a rubber mat with various patterns and are stamped onto freshly laid concrete after half hour or so (depending on concrete mix).

Stenciling from what I understand originates from Australia. Their methods are somewhat different. It comes in rolls of selected patterns. It is a few mm thick. Erm, they look like netting (best description my brain can think of lol). Laid on concrete and then removed when dry. If I am not mistaken, this cost more than stamping.

Both methods I have seen how it is done first hand.