To be brief, digital printing uses toners on a press, which makes it very similar to your office printer, while litho printing uses wet ink and printing plates. For longer runs, litho printing is best – that’s for upwards of 2,000 – while for the shorter runs digital is cheaper.
The reason for that is that litho printing requires a lot of time involving a skilled worker to set up the run – making plates, and so on – before printing can begin. Digital printing involves using dots of colour and electronic files such as a PDF.
With litho printing, the inked image is transferred on to a rubber blanket from a printing plate, and then transferred again on to the paper. If the job is in full colour it means that the artwork has to be transferred on to four different printing plates, each of which produces one of the four colours – black, yellow, magenta, and cyan – so four runs are needed to complete the work. Of course, if fewer colours are requires – say three- then only three plates will be needed, so the job is less expensive.
Litho printing is generally reckoned to be much better for large areas of solid colour, and the recent use of CTP (computer to platemaking) together with computer control of presses has helped to speed up the process.
Turnaround time with litho printing will usually be of the order of five days, because there has to be time allowed for the ink to dry.
On the other hand, digital printing is very cost effective for small print runs for the simple reason that there is far less set-up time involved, and the job needs no drying time. Also, jobs can be personalised: this means that a mail shot, for example, can say “Dear Jim”, “Dear Susan”, etc.
Other considerations include the fact that litho printers can print on a wider range of materials than digital, and it used to be the case that they would produce a better finished result. However, digital printers have caught up to the extent that even many print workers can no longer tell the difference.