The difference between an abbey and a cathedral is primarily one of function and ecclesiastical authority rather than architectural style. A Cathedral is the "principal church" of a diocese and serves as the official "seat" (or cathedra) of a Bishop; it is the administrative and spiritual center for a large geographic region. In contrast, an Abbey is part of a monastery or convent and serves as the place of worship for a community of monks or nuns living under the authority of an Abbot or Abbess. While a cathedral is open to the public for regular diocesan services, an abbey's primary purpose is to facilitate the private, communal prayer life of its resident religious order, though many historic abbeys (like Westminster Abbey) now function similarly to public churches. Essentially, a cathedral is defined by its status in the church hierarchy (the Bishop's home base), whereas an abbey is defined by its inhabitants (a self-contained religious community). This is why a city can have multiple abbeys but generally only has one cathedral per denomination, as there is typically only one Bishop per diocese.