The Microsoft SQL Server Development Customer Advisory Team has a nice blog post about Distributed Partitioned Views / Federated Databases
They cover the following definitions
Definition 1: Local Partitioned View – A single table is horizontally split into multiple tables, usually all have the same structure.
Definition 2: Cross Database Partitioned View – tables are split among different databases on the same server instance
Definition 3: Distributed (across server or instance) Partitioned View. Tables participating in the view reside in different databases which reside on different servers or different instances.
Make sure you read the list of 13 items under Lessons Learned on Distributed Partitioned Views: (multiple servers involved)
Link to the article: http://blogs.msdn.com/sqlcat/archive/2007/06/20/distributed-partitioned-views-federated-databases-lessons-learned.aspx