What is metal printing, metal printing and metal color printing? What's the difference between them?

Metal printing refers to the printing in which the substrate is metal, that is, the pattern is printed on metal, not on paper. Metal printing is a kind of metal printing, but the printed pattern is a pattern, and metal color printing is also metal printing, but the printed pattern is a variety of colors, and there is no special difference. For example, cans belong to metal printing, monochrome can belong to metal printing, and multicolor belongs to metal color printing, which requires multi-process printing of different colors, that is, overprinting.