SSRS Interview Questions - What is the difference between Data Source and DataSet in SSRS

Data Source 

is a set of data source connection properties. When we create data source, we need to provide below information
Name: Name for the Data Source
Description: Optional, Good idea to provide
Connection Type:  Such as Microsoft SQL Server, Oracle, OLE DB and ODBC etc.
Connection String: Provide the Connection String for Data Provider
Credential Type: Specifies how the credentials are obtained for connection

But DataSet

represents the data returns by running query on Data Source in SSRS Report. For query you can have simple Select statement or you can use Stored Procedure. Report definition does not contain data but it contains query command,fields collection, parameters,filters and data options that include case sensitivity and collation.