Sub-Report and Linked Report

A Sub-report is a report that displays another report in the body of a main report. It's used to embed a report within a report.  Any report can be used as a sub-report . A sub-report can use different  data sources other than the main report.

A Linked Report is a report server item that provides an access point to an existing report. A linked report is derived from an existing report and retains the original's report definition. A linked report always inherits layout and data source properties of the original report. You can create a linked report when you want to create additional versions of an existing report.