The DataStage tool was the first to support Parallel processing, while the Informatica does not support such processing.  In terms of Slow changing Dimensions (SDC), the DataStage supports complex methods or custom scripts while it's quite easy in Informatica to implement.  Version control is unavailable in DataStage while it is supported in Informatica.  DataSatge supports a large number of data transformation blocks compared to Informatica.  The DataStage lacks the lookup, while the Informatica supports the powerful dynamic cache lookup.