What is the difference between OLEDB Provider and SqlClient ? Which is more productive to use for Dot Net application?

Answer:

Generally SQLClient .NET classes are highly optimized for the .net / sqlserver combination which in-turn gives accurate results. The SqlClient data provider is fast. It works faster than the Oracle provider, and even more faster than accessing database through the OleDb layer.

Reason for being faster is, it access the native library which generally gives you a better performance and it has also got a lot of support from SQL Server team online.