Difference between Mapping Parameter and Session Parameter

Mapping Parameter	Session Parameter
Mapping parameters are user defined variables defined at mapping level or using parameter files.	Session parameters are used for specific purposes like defining connection name or input file name or bad file name or lookup file name or output file name
Mapping parameter is set at the mapping level	Session parameter is set at the session level
Mapping parameter dose not change from session to session.	Session parameters can change from session to session
Mapping parameter uses '$$'	Session parameters uses '$'
Example: $$Datasource_num_id	Example: $DBConnection_[Name] $InputFile_[Name] $OutputFile_[Name] $LookupFile_[Name] $BadFile_[Name]