CD-Text is written to parts of the disc that are not normally used
CD-Text is only applicable to CDDA disc, not mp3's
mp3's use metadata known as id3 "Tagging", which is data actually embedded in the files themselves.
CD-TEXT includes only Artist, Album & Track title (not all players
are cable of displaying any, let alone ALL of this information)
id3 tags can include a large amount of information, not only Artist, Album & Track, but composer, release date and a host of other data including lyrics
and even album art.
a good explanation of CD-Text can be found on Wikipedia
Wikipedia on id3 "Tagging" is a better explanation than I have time or inclination to type:
Read these and you have the proper primer to get into the finer points