What do the rankings alongside ones name indicate?

[Cyclopathic]

Member, executive member, president and so on. I'm not a beginner but I've posted this here because it seemed like a bit of a nooby question. So what do the rankings signify and how are they decided. Is there any advantage from gaining a higher ranking? Can one be demoted?
For ages I was posting here thinking that the higher sounding rankings were really moderators or at least some one involved in running the site.

 

[lukesdad]

Post count no more no less.

 

[Cyclopathic]

Post count no more no less.

It's good to know that I won't always be known as a "member" of some description or other.