Teradata OLEDB Access Module versus versus OLEDB adapter

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Teradata OLEDB Access Module versus versus OLEDB adapter

When do I want to use each of these? If I have a source OLEDB system and am continually moving data from there to Teradata via scheduled SQL jobs on the Teradata side, I like that OLEDB Access supports FASTLOAD functionality. Are there limitations to OLEDB access module that would prevent me from using it?

Thanks!