Most drops depend on the level of your opponents/area. A level 24 opponent will drop different stuff then a V3 opponent. A chest in a level 32 area will have different contents then a chest on an V10 area.
Unless you are in cyrodil... there drops depend on -your- level, no matter the opponents.
Veteran zones are all one veteran rank, but normal levelling zones have a certain range... and so do set items, or materials used to make gear. It is entirely possible that in one zone "range", you may start with one and proceess to the next gear drop "ranges"...