Block Mode
A block is recorded in a certain mode:
Audio, M1, M2, M2F1, M2F2, DVD mode
On CD all Blocks contain 2352 bytes. This is what you end up with if you extract raw. Depending on the Mode, the user data portion is different.
Furthermore, every block is accompanied by 8 sub-channels. Each sub-channel can contain 12 bytes. The P and Q sub-channel bytes are the most important and contain data necessary for correct operation. They are tampered with the most in case of copy protections. The other sub-channels can contain data but are seldom used and not many CD readers can actually correctly retrieve all that data. CD-Text is located in the sub-channel bytes in the lead-in.
On DVD the story is completely different. DVD only knows one Mode (DVD Mode)