What is the difference between digital printing and digital printing?

Nothing different, it's just called something different!

If you want to make a distinction, digital printing can be divided into two categories: Plateless printing and Plate printing

Plate printing is similar to traditional printing, except that it is all computerized (DI Direct Imaging Platemaking). The digital press eliminates the need for traditional PS plates, and the number of impressions is irrelevant to the cost per unit.

Both of these claim to be express printing!

Both claim to be fast!