Personal Connection : A Personal connection is created by one user and cannot be used by other users. The connection details are stored in PDAC.LSI file.
Shared Connection : A shared connection can be used by other users through a shared server. The connection details are stored in SDAC.LSI file in the Business Objects installation folder. However one cannot set rights and securities on objects in a shared connection. Neither can a Universe to exported to repository using a shared connection.
Secured Connection : A secured connection overcomes these limitations. Through it rights can be set on objects and documents. Universes can be exported to the central repository only through a secured connection. The connection parameters in this case are saved in the CMS