Question: What's the Difference Between a Dummy and a Comp?
A dummy and a comp (short for comprehensive artwork or composite design) are both mock-ups of work done by graphic designers.
Answer: Generally comps are the preliminary layouts of several different design options that you show to a client for them to choose from. Some designers may show the client sketched thumbnails. Others may present more complete comps, in full-size, with actual text and images in place -- only missing some finetuning of images and type.
A dummy may be for internal use, ideas for layouts use placeholder text and graphics. Or, you may give your printer a dummy of your design showing how it is to be assembled. This would probably be a laser-printout of your document, trimmed to the final dimensions and folded.
The terms comp, dummy, and mock-up may sometimes be interchanged, but in general a comp is in the early stages of the design process and a dummy is for internal use or for showing the "mock-up of a finished piece" to your printer.
