Acronyms are invented so the more knowlegeable can communicate at faster speed. For novice, its a barrier of course. Here are some usefully summaries. Sorry if I geek out in Acronyms in the spirit of this section :)
The diagram in Overview are full of these acronyms so look over those pics.
This is a partition on the boot drive that boots first. OS boots later. Stands for Extensible Firmware Interface Can easily imagine why OCLP wants to insert its own code (often just called OC) into the EFI
AMD's graphics architecture name (Graphics Core Next) Each generation of architecture are usually completely different with very different drivers.
GCN v1-3 appears to have similar drivers
CGN v4 completely different
Open Core. This is part of the OCLP software that goes into EFI. So basically new software developed by the OCLP team that runs when the Mac boots. Need to do this to properly setup and communicate with rest of the system / booting process.
They thought the acronyms were challenging too haha. Link