There are different titles and they all depend on how many posts you have made. Not scientific or ideal but it's the best option we have. We could scrap them altogether but it does allow people to know who talks to much and who maybe should be given a little bit of slack because they haven't been around that long. Doesn't always work out that way mind you.
It's not all about titles, each title is a profile on the forum - meaning that as you progress up the title list, you could access more forums and on CBF specifically, see less adverts. Guests see loads, then they lessen as you join, move up from newbie (which from memory might be when you have made 50 posts but I'll check).