The ESO pvp set category contains all PvP sets that drop from Cyrodiil, Imperial City and Battlegrounds. As well as the sets that can be crafted inside Cyrodiil and Imperial City.
You can learn more about each pvp zone here:CyrodiilImperial City
& Imperial SewersBattlegrounds
Each set page has detailed information on where you can find the specific sets for Cyrodiil, Imperial City and Battlegrounds.