Toner is finely powdered ink used in digital printers.
During the digital printing process, the toner is electrostatically charged to adhere to the printer drum charged with opposite polarity (so negative attracting positive). After transferring to the paper, the toner particles are then fused in place (adhered to the paper) by a heat fuser such as a heat roller.
ElectroInk technology (used on Indigo Digital Presses) uses small colour particles suspended in Imaging Oil (also known as Isopar) that can be attracted or repelled by means of a voltage differential (again negative attracting positive and so forth).
The ink forms a very thin and smooth plastic layer on the paper surface. The fact that these particles are so small ensures that the printed image does not mask the underlying surface of the paper (whether it be rough/ smooth, gloss/ matte, etc.), which is possible with some toner-based processes, bringing Indigo Printing closer in appearance to conventional offset lithography, whereby ink is actually absorbed into the paper.
Inkjet technology works by spraying very fine drops of ink on a sheet of paper.
These droplets are ‘ionized’ which allows them to be directed by magnetic plates in the ink’s path. As the paper is fed through the printer, the print head moves back and forth, spraying thousands of these small droplets on the page. Inkjet can print finer, smoother details and are often chosen to produce high quality photographic prints.