The digital permanent is a perm that uses hot rods in which the temperature is regulated by a machine with a digital display, hence the name. The biggest difference between other perms and a digital perm is the shape and the texture of the wave.
The digital perm makes the wave most prominent when the hair is dry, and loose when it's wet. Therefore, you can create the dry and curly look of the curling iron or the hot curler. A digital perm can create loose waves and curls, which is difficult with regular perms.