The ConnectionString specifies the database that contains the report data. The RecordSource property specifies which table, stored procedure, or Sql command to use for retrieving the data.

If you want to use a different type of connection (e.g. a System.Data.SqlClient.SqlConnection, or if your application already has the data available in a System.Data.DataTable object, you can assign the data directly to the Recordset property.

Reference

DataSource Class
DataSource Members