An abstract class may contain complete or incomplete methods.
Interfaces can contain only the signature of a method but no body. Thus an abstract
class can implement methods but an interface can not implement methods.
An abstract class can contain fields, constructors, or
destructors and implement properties. An interface can not contain fields,
constructors, or destructors and it has only the property's signature but no
An abstract class cannot support multiple inheritance, but an interface
can support multiple inheritance. Thus a class may inherit several interfaces
but only one abstract class.
A class implementing an interface has to implement all the
methods of the interface, but the same is not required in the case of an abstract
Various access modifiers such as abstract, protected, internal, public,
virtual, etc. are useful in abstract Classes but not in interfaces.
Abstract classes are faster than interfaces.