The castor based fluid is not in common use - it was used in stuff like light aircraft brakes many years ago. I think it was dyed blue, although I could be wrong there; it may be alcohol-based fluids that are blue dyed.
Technical study books still refer to it because they've never got around to changing the subject matter. It's there more as a historical reference than anything else.
So basically, you've got just two types.
If you want a good training and reference source, I found the ATP series of books very helpful.
http://www.atp.com/