Use a data source as output when you want to create a target mapplet. Use an Output transformation in a mapplet to pass data through the mapplet into a mapping.
Use one or more data sources to provide target data in the mapplet. When you use the mapplet in a mapping, it is the last object in the mapping pipeline and contains no output ports.
Use an Output transformation to pass output to a downstream transformation or target in a mapping. Each connected port in an Output transformation appears as a mapplet output port in a mapping. Each Output transformation in a mapplet appears as an output group. An output group can pass data to multiple pipelines in a mapping.