var vs dynamic

• 
  
• In case of var type is decided at compile time by compiler=>Complie time Type Interference.
• As per MSDN,-
           var is a strongly implicitly typed local variable for which the compiler is able to determine the type from the initialization expression.
• Introduced in 3.5
• 
  
• In case of dynamic type is decided at runtime=>Run time Type Interference.
• As per MSDN,-         dynamic lookup allows you to write method, operator and indexer calls, property and field accesses, and even object invocations which bypass the normal static binding of C# and instead gets resolved dynamically.
• Introduced in 4.0

Example:-

string MyString="Sukesh Marla";
var MyVarVariable=MyString;
Response.Write(MyVarVariable.MyMethod());

when we run the above code,we get a error  'string does not contain a definition for 'MyMethod' and no extension method 'MyMethod' accepting a first argument of type 'string' could be found (are you missing a using directive or an assembly reference?
means var knows that what is assgned to it.

string MyString="Sukesh Marla";
dynamic MyVarVariable=MyString;
Response.Write(MyVarVariable.MeMethod());

this will get complied.

and throws exception at runtime,if you wont define any extension method MyMethod for string class.