Default Question on flashing/rooting/bootloaders/upgrading/terminologies...

I'm getting my Note 3 (international variant I believe... I'm in Singapore) soon and I just want to clarify a few terminologies related to all the topics in the title.

I understand AP refer to PDA, CSC refer to consumer software customization (specific to geographical region) and CP I have no idea.

Then, what are MJ1/MJ7/MK4? I know they are codes that refer to version numbers (year month and revision no.) but are they version numbers of firmwares, or PDA, or CSC, or what? For example in this thread (http://forum.xda-developers.com/show...0853&nocache=1) the guy has AP MJ1, CP MI2, and modem MJ1. Why aren't they all the same?

When ppl say like MJ7 has the knox-enabled bootloader so don't update to it or you can't ever downgrade again, are they referring to MJ7 firmware/AP/CP/CSC? Since all of them have similar identifiers which may differ, how do I know what they are referring to?