What is the difference between friends and following?

Friends is mutual: you send a request, they accept, and you then see each other in your friends list and can see when the other is online.

Following is one-way and needs nobody's permission: it puts that person's posts in your Following feed. They are notified that you followed them, but they do not have to do anything.

Friends carry across Creta — the same list appears in the games and clubs desktop app.