Letterpress printing is the original printing technology, and is done by inking a raised (relief) surface and pressing it into the paper. This produces a debossed indent in the paper as a side effect of applying the ink, which is unique to this printing process.  Foil stamping is a letterpress process that uses heat to fuse metallic foil to paper, instead of ink.  Digital printing, also sometimes known as flat printing, is a high quality type of inkjet printing. While it has limitations in the type of paper it can print on and color matching, it is very flexible in the kinds of imagery it can print (photos and reproductions of watercolor or drawing are not a problem, unlike letterpress printing).  It is also relatively inexpensive at small quantities, compared to traditional printing processes.