Authored content is content that only one user can edit. It’s best for guide makers who want to have complete control over the guides they make. For example, if you were making a guide for a Zelda game where you beat it without any heart pieces, you wouldn’t want other people to be able to edit it because you’re doing it in a unique way not necessarily the best way.
Wiki content is content that anyone can edit. The idea behind this content is that everyone will contribute to one guide and be constantly improving it. For example, if you’re really good at a certain boss in God of War 3 you add your strategy for just that part and someone else can add their strategy for a different boss that they’re better at.