How to distinguish the spot color and four color CMYK printing of tin box packaging?

1, Spot color printing
Spot color is based on Pantone chart, first to set printing ink and then to print so you only get one color. Also it can make in a different shapes and patterns according to customer’s need. Several spot colors are superimposed to create different colors and patterns. Since spot color is single color, so there is no dot on the surface, it looks relatively smooth.

2, CMYK printing
CMYK printing is based on cyan、magenta、yellow and black, it is printed by means of offset printing (like paper printing). If you look closely with a magnifying glass, you can see that there are some dots on the printing (like a television display, they are pixels when magnify many times). So CMYK printing is actually a combination of dots.

3,How to choose spot color and CMYK color?
Generally speaking, if you need to produce some complex patterns tin box, we suggest to choose CMYK printing. If patterns simple, only one or two colors on it, especially large areas of single color then we suggest to choose spot color. 
So in a four-color pattern, if there is a large area of single color, you can choose large area CMYK printing and single spot color printing together. Of course, the final production cost of tin  box packaging is a little higher.