What is the Difference between Const and Readonly

Const:

      1.    Const can only be initialized at the time of declaration of the field.
      2.    Const values will evaluate at compile time only.
      3.    Const value can’t be changed these will be same at all the time.
      4.    This type of fields are required when one of the field values remains constant throughout the system like Pi will remain same in your Maths Class.

Read-only:

     1.    The value will be initialized either declaration time or the constructor of the class allowing you to pass the value at run time.
      2.    Read only values will evaluate at runtime only.