At CBR Preferred has to do with proximity to the food court (Old Port Royal). You would be somewhere in the first three buildings of Martinique (24, 25, or 26) or else in Trinidad North (31, 32, 33). Your room may face a quiet pool, lake, courtyard, or parking lot. My preferred room in Martinique 24 faced a courtyard, even though I requested lake view.
The water view rooms are scattered all over the resort and may be facing the lake, a quiet pool, fountain, bird bath, etc. It may be in a building furtherest from the food court, but if you can spot any water from it, it's considered a water view. I might pay more for a preferred room at CBR, but never would for a water view.