While these two types can cross over, Illuminated and Digital Traffic Signs aren’t necessarily the same thing.
Digital Electronic and Illuminated Road, Highway, Traffic, Street Airport Signs
Digital traffic signs are typically lighted with LED’s (Light Emitting Diodes) and may have a small section that shows a number or series of numbers and letters, such as you might see at some airports, or may be an electronic reader board with messages for oncoming motorists.
Illuminated Traffic Signs
Illuminated Traffic Signs, on the other hand, may include digital kinds, but may simply be a signpost that is lighted from below with directional lamps,