Crystal Reports and Crystal Server are two different pieces of software.
There are many differences between Crystal Reports and Crystal Server, but simply put:
Crystal Reports is used to design/modify/manipulate/create the actual report from a multitude of separate data source locations.
Crystal Server is used to view or send the completed reports to user. The server contains an interface that allows users to access on-demand reports based on security levels or authorization. You can also schedule auto-reports to be sent on scheduled dates and time.