Difference between Abstract classes and Interface

• Abstract Class
• A class may inherit only one abstract class.
• An abstract class can contain access modifiers for the subs, functions, properties.
• An Abstract class has abstract or concrete subs, functions, properties etc.
• An abstract class can have fields and constants defined.

 

• Interface
• A class may inherit several interfaces, which help achieving Multiple Inheritance.
• An interface cannot have access modifiers for the subs, functions, properties etc everything is assumed as public
• An interface can only have abstract subs, functions, properties etc
• No fields can be defined in interfaces 

Ref- here, here