Bjarky is PMS'ing, so excuse the angry tone.
Fiefs meaning castles or player owned settlements?
Caravans?
How do I know if the price is higher? By going there and looking or can I look it up before?
Fiefs are Villages, Castles and Towns. All of them are player owned.
A caravan is when you buy goods in one fief and then move to another that's far, far away. You then get a distance % bonus when you sell them.
Before you would have to go the the fief to check the price there, now you can just click on the fief on the map and it will give you the "price" in that fief. Note that the "price" is only the base price, so distance bonus is not shown there.