Microsoft underbara förklaringar: ;)
ADO
ADO is Microsoft's strategic, high-level interface to all kinds of data. ADO provides consistent, high-performance access to data, whether you're creating a front-end database client or middle-tier business object using an application, tool, language, or even an Internet browser. ADO is the single data interface you need to know for 1- to n-tier client/server and Web-based data-driven solution development.
OLE DB
OLE DB is Microsoft's strategic low-level interface to data across the organization. OLE DB is an open specification designed to build on the success of ODBC by providing an open standard for accessing all kinds of data.
ODBC
Open Database Connectivity (ODBC) is a widely accepted application programming interface (API) for database access. It is based on the Call-Level Interface (CLI) specifications from X/Open and ISO/IEC for database APIs and uses Structured Query Language (SQL) as its database access language.
ADO Dokumentation: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/ado270/htm/dasdkadooverview.asp
OLE DB Dokumentation: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/oledb/htm/dasdkoledboverview.asp
ODBC Dokumentation: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/odbc/htm/dasdkodbcoverview.asp
Hoppas det ger nåt.