Component involves the use of three separate video cables (usually red, green and blue when commercially purchased which correspond to same colored inputs on display device) that can carry a high definition or digital video signal. You must still connect a set of audio cables. Composite involves the use of one video cable and a two pronged audio cable. Standard definition is all such a video connection will carry. There is techinical stuff. Jan Vigne or King Tapeman, among others, could give you that info if you are interested.
Component inputs are analog, period. You can't send a digital signal to an analog input. Try sending that digital audio signal to an analog input, you'll get nothing. Like I said before, if you want a digital signal, you have to use HDMI or DVI.
I understand and agree with your response, but my question has more to do with the characteristics of the cable itself. What would prevent the cable itself from carrying a digital signal?