FOUR COLOR VS. SPOT COLOR
The big question when it comes to color in printing is: four color process or spot color? The answer to this question often-times determines how the job is printed, but it also determines how your files is built in the first place. So how do you know which is right for you; process or spot? To know the answer to that question, you must first understand the difference between four color process (CMYK) and spot color.
What's the Difference?
Four color process is the most familiar type of printing. Many in-home printers use four color process, and both digital and offset printers can use four color process as well. Four color process involves four colors (cyan, magenta, yellow, and black) being laid down on paper in a dot pattern that, if done right, translates to a full spectrum of color to the human eye. A great way to see and understand this process is to look at a newspaper, where the dots are large enough to be seen individually.
Spot color is different from four color process in that each color is individual, mixed separately before being used for printing. The most well-known standard for spot colors is the Pantone Matching System. You can find a spot color is almost every color imaginable, as well as specialty colors including metallic and neon.
Additional Pointers
Four Color
Four color process is the only way to print full color images. Spot colors cannot capture the full spectrum of color.
Solid areas of certain colors can be difficult to match and maintain consistency with four color process, because dots of different colors are being used. This is a situation where the purity of a spot color may be most appropriate.
Thin lines are difficult to print with a four color process, because of the use of dot patterns. The lines can appear jagged or uneven.
Printing small items digitally, with four color process, is often the most economical, especially for short-runs or small items.
Spot Color
Solid colors are best for brand materials because they will produce the most consistent colors across lots of media.
Because spot colors are specialized, you are limited on the number of colors that can be used on a press, and thus the number of colors in the project itself.
Spot colors can produce brighter and more unique colors than four color process.
Spot colors cannot typically be printed on a digital printer, which makes their cost higher in some situations, but if less than four colors are used on an offset press, the price can be comparable to four color process.
H/T: PaperSpecs