From Silver Sun Republic Codex

A Fiefdom is a land grant given to a Knight in exchange for their service or as part of the terms of vassalage for a foreign entity. Fiefdoms generally consist of the feudal lord, their Great House and any vassals (mostly Contadini or Commoners) or free citizens (Popolani) who serve as House Artisans. Fiefdoms are generally military oriented while a Baronetcy is more geared towards economic production.