What is the difference between Interface and Abstract Class in C#?

Difference between Interface and Abstract Class

Below are the common points to be remembered,

• Abstract classes can have abstract plus nonabstract methods while Interfaces all methods needs to be abstract only.
• Abstract classes can have variables and method implementation whereas Interfaces are not allowed to declare variables and the methods are abstract only. (No implementation)
• Abstract class members are private by default even they can be changed, In Interface it is public by default and you cannot change the same.
• To declare abstract classes Abstract keyword is used, for Interface it is Interface
• Abstract classes and Interfaces are not allowed to create an instance.
• Abstract classes can have a constructor but Interface do not.