What is the difference between Steelray Project Exporter for UN/CEFACT XML and Steelray Project Exporter for IPMDAR?

Steelray Project Exporter for IPMDAR is an add-in to Microsoft Project which exports Microsoft Project schedules to the IPMDAR SPD (Schedule Performance Dataset).
Steelray Project Exporter for UN/CEFACT XML is a free add-in to Microsoft Project which exports Microsoft Project schedules to the older IPMR Format 6 -- the IMS (Integrated Master Schedule).