ISRC codes are for your royalties.

and archiving purpeses. (cddb)
ISRC codes are given 2 you(or your record label)
every time you song gets play'd on the radio, your ISRC code is stored.
video clips also have ISRC codes.
usely the mastering engineer playses the codes on the disc.
cd text and cddb are 2 diff. puppys
CDDB can be added when you burn your projetct (audio files) in Nero,wavelab,itunes.
cddb is a database that stores info of the project on a server. and itunes,Nero,mediaplayer,ect,ect have acces 2.
CD TEXT can also be added in those programes. but only supports cd/dvd players that can read CD TEXT.