According to ADO: ActiveX Data Objects, a book by Jason T. Roff, published by O’Reilly Media in 2001 (excellent diagram here), he says precisely what MOZILLA said.
(directly from page 7 of that book)
- ODBC provides access only to relational databases
- OLE DB provides the following features
- Access to data regardless of its format or location
- Full access to ODBC data sources and ODBC drivers
So it would seem that OLE DB interacts with SQL-based datasources THRU the ODBC driver layer.
I’m not 100% sure this image is correct. The two connections I’m not certain about are ADO.NET thru ADO C-api, and OLE DB thru ODBC to SQL-based data source (because in this diagram the author doesn’t put OLE DB’s access thru ODBC, which I believe is a mistake).