What do the terms "BL", "AP", "CP", and "CSC" mean in Odin?
CSC (Consumer Software Customization): It is specific to geographical region and carriers. It contains the software packages specific to that region, carrier branding and APN setting.
PIT (Partition Information Table): You only need it if you screw up your partition table or if the firmware specifically requires it because of a change in the partition table layout.
BL (Bootloader): As its name implies, this option is used to flash the Bootloader of the device.
AP (Application Processor or PDA): Android.
CP (Core Processor): We call it Modem.