Bootloader:

You cannot change the Codespace if it has been protected.
You cannot access the Configuration Fuses
You cannot access the ID (Serial Number) Bytes.
You CAN read back Codespace (even if it has been protected) with a suitably enabled Bootloader... but I'm NOT going to tell you how.

ICSP:

You can change the Codespace if it has been protected.
You can change the Configuration Fuses.
You can access the ID (Serial Number) Bytes.
You cannot Verify if the Codespace has been protected.
You cannot change back the protection fuses (once a PIC is protected, it remains protected).

Melanie