The difference between Digital and litho is that litho is normally used for much larger print run.. normally 1000>, it also normally gives a better quality over digital. But for quantities below 500, you are most cheaper to go digital.
The best digital printers nowadays can get really close to the quality of Litho and they also don't need to be set up. for instance, if you go litho, you need to produce a set of plate which are used in the printing press to produce your print. with digital, its click and go.