Thermal Transfer Printing
Thermal transfer printing is a digital printing process in which ink is applied to paper (or some other material) by melting a coating of ribbon so that it stays glued to the material on which the print is applied.
It contrasts with direct thermal printing where no ribbon is present in the process. It was invented by SATO corporation around the late 1940s.
Direct Thermal Printing
Thermal printing (or direct thermal printing) is a digital printing process which produces a printed image by selectively heating coated thermochromic paper, or thermal paper as it is commonly known, when the paper passes under the thermal print head. The coating turns black in the areas where it is heated, producing an image. Two-colour direct thermal printers can print both black and an additional colour (often red) by applying heat at two different temperatures.
Thermal printing is notable for being the only form of (non-embossing) printing which involves no ink.