Conventional mammography uses X-rays to look for tumors or suspicious areas in the breasts. Digital mammography also uses X-rays, but the data is collected on computer instead of on a piece of film. This means that the image can be computer-enhanced, or areas can be magnified. Eventually, a computer could in certain appropriate situations, screen digital mammograms, theoretically detecting suspicious areas that human error might miss.
(Top) Breast images using conventional mammography. (Bottom) Digital mammography images of the same woman. Images courtesy of Dr. Laurie Fajardo, Johns Hopkins Medical Institutions