wikipedia's article. I was concerned that a) proper guilds weren't around during the historical analogy I'm using (roughly CE 1310), and b) "guild" wasn't a Germanic term. Now that I've read the WHOLE wikipedia article, it appears that I was mistaken.
It turns out that Germany had a "thriving" guild community by CE 1300, and they were in fact called "guilds." I'm fine with changing that. Howevah, my original idea was to have "misteries" in Cerai, because I picture things being more sophisticated, secretive, and bureaucratic (for lack of a better word) over there. I swear the last time I read that article they were spelled "misteries," but it looks like "mysteries" is going to be the way to go.
So to answer your question, I picture every organization in Cerai being a "mystery," whereas every organization in the Blackwood would be a "guild." Chivalric orders are, obviously, their own thing. There won't be an organization for everything under the sun (dockworkers, for instance, are probably not skilled enough to merit their own mystery), but I think it's fine to have things like "Glassblowers' Mystery" and "Trade Mystery."
The real-life equivalents were usually groups that held skills and knowledge in the utmost secrecy, and they were usually pretty mundane crafts. The Freemasons are a great example; their organization revolved around knowing how to lay stones properly (pretty boring all-in-all), and they kept it a secret because they didn't want any competition. However, just look at their portrayal in popular culture today, and you get an idea how carefully they guarded their secrets.
Of course, the only guilds that PCs are likely to interact with (and thus the only ones I'll develop) will be the classic stuff that you mentioned, plus maybe a few more. That doesn't mean that really mundane things wouldn't also have their mysteries and guilds, though.
That's basically what I'm picturing. Also (in Cerai), I think it would be cool for every "shady" Mystery to have a legitimate front. For example, the Mystery of the Most Excellent Craft of Glassblowing would be focused on teaching its members the best way to blow glass for windows, chalices, vases, etc., and they'd be one of the biggest guilds since Cerai is nuts about glass. Master Glassblowers can create colored panes that dance with the sun's light, but the members of the most elite circles of the Mystery are said to know the secrets of manipulating shadows too. These elite are rumored to be master spies, capable of hiding in broad daylight and observing things from great distances.Do you want to roll a cart down the street, crying out that you sell gently-used knives and kitchen tools? Go right ahead; your wife and children will accept what meager food you can provide with grace according to their station. But if you want to learn the secrets of true salesmanship, you must join the Mystery of the Most August Tradesmen.