Whatare the differences between LINQ to SQL v LINQ to Entities, well:

LINQ to SQL uses tables as entities

LINQ to Entities allows me to write C# LINQ queries that run against a conceptual data model.

The following table provides a summary of the features within each LINQ object

So this means that LINQ to SQL uses a database model to create its entities, where as the Entity Framework work on a layer of abstraction above the data, this is a most important feature.  As most database changes are taken care of by the schema and mapping without requiring a change to the obect model – making it so you do not have to refactor and rebuild your objects.

The second difference is the Entity Framework has the ability to allow the entity inheritance and entity composition.  This means that you can create an entity that is composed of colums originating in multiple tables without any complex join logic.

In summary:

• If you want the added security of insulation and loose coupling from the underlying database schema to make your object model more resilient to change, use the Entity Framework
• If you find that you need the features of entity inheritance and entity composition, use the Entity Framework
• If you already have a large LINQ to SQL codebase that is running just fine without entities, you probably don’t need to spend the time to refactor out LINQ to SQL to replace it with LINQ to Entities.
• If you want to run LINQ queries against an object model, but your object model is a 1:1 mirror of the tables in your database, you probably don’t need the Entity Framework.