Digital cables

Uninformed as I am, and the question may be as dumb as it appears: Which components are linked by a digital cable versus a pair of interconnect cables? Are CD/dvd/sacd players not typically connected to a preamp or integrated amp via interconnect cables as opposed to digital cables?

If you use a CD player then you are correct that your integrated player (which combines in a single box your CD transport, digital de-jitter device, and inboard digital to analog converter), has analog RCA output jacks to send separately the analog left channel, and the analog right channel to your pre-amp's RCA input jacks marked for receiving left, and right channel analog CD input.
The use of a digital interconnect refers to connecting a separate CD transport to a separate digital de-jitter device, and on to a separate digital to analog converter.
Single, digital interconnects connect these separate, presumably higher performing, stages when the CD signal is still being processed, and passed along, in the digital domain where a single digital cable carries information for both stereo channels. Your integrated CD player performs all these connecting digital steps inside one box, and eliminates the need for any digital interconnect.