The general guides will focus on fundamentals of tanking
The beginner guides will cover the basics of tanking. They will ignore nuance for the sake of simplicity and provide a single skill setup with very few gear setups that might not be perfect for any situation, but will be good enough for most situations.
The advanced guides will try to cover almost every possible situation a tank might find themselves in. They will cover multiple skill setups and gear setups for different situations, sometimes very obscure ones, and they will be a long read.