Difference between LINQ to SQL and LINQ to Entity（DataContext and DbContext）

http://msdn.microsoft.com/en-us/library/cc161164.aspx

http://stackoverflow.com/questions/2443836/what-is-the-difference-between-linq-to-entities-linq-to-sql-and-linq-to-da

http://social.msdn.microsoft.com/Forums/en-US/ad257e81-fc5c-4286-a899-9f07135669d4/difference-between-linq-to-sql-and-linq-to-entity