Another vastly misunderstood topic. While the definition from Microsoft is very clear, there are subtleties to confound us. Much of our expectations of RDL are set by automatic behaviors in Report Builder and in Visual Studio Report Designer. These are both tools with overlays for RDL and don't necessarily represent everything that RDL is capable of doing in the hands of an expert programmer. The Microsoft definition for RDL versus RDLC follows in green text.
Comparing RDL and RDLC
RDL and RDLC are defined by an XML schema called the Report Definition Language.
The schema for both file formats is identical and can be found at http://schemas.microsoft.com/sqlserver/reporting/2008/01/reportdefinition .
However, the files have the following differences:
The <Query> element of RDL contains query or command information and is used by the report server to connect to the data sources of the report.
The <Query> element is optional in an RDLC file. This element is ignored by the ReportViewer control because the ReportViewer control does not perform any data processing in local processing mode, but uses data that the host application supplies
In general, one can assume that RDL works in the remote (i.e. SSRS or Report Builder or "web).