What does initializing and formatting a drive do (part 2- GPT)

Part 1 explains what happens on the bit level when you initializing a drive with MBR https://www.youtube.com/watch?v=2Yksg1A8T9U

Part 2 will explain initializing a drive with GPT

Part 3 will explain formatting a drive ... https://www.youtube.com/watch?v=ZTNd60fPTr8