I am always confused as to what is meant by the term ADO.NET. For example, are Entity Framework and Linq-to-SQL considered ADO.NET or is ADO.NET only the types contained in System.Data?
If I'm connecting to a database with System.Data.SqlClient, would I be correct in saying I'm connecting using ADO.NET or is there some other terminology for this?
If you are using System.Data.SqlClient your answer should be ADO.NET.
You can see Linq2Sql as building on ADO.NET and EF is too. EF can be seen as a replacement or improvement over Linq2Sql - but you can still use DataSets, Linq2Sql or EF - it's a matter of taste. For some applications EF is just to much ceremony.
EF is just the way MS is heading with ORM at the moment. Both of the older technologies are supported but only EF is actively developed as far as I know.