Difference Between abstract Class and interface

Difference Between abstract Class and interface
Abstract class having method declaration as well as method method definition whereas interface having method declaration only.

2>Abstract class are known as partial abstract class whereas interface is known as fully abstract class.

3>Abstract class features we have to inherit to the child class whereas interface features we have to implement in the child classes.

4>Abstract class support access specifiers whereas interface doesn't support access specifiers.

5>Abstract class have normal variable as well as constant variable whereas interface have only constant variables.

6>We can write constructor in abstract class whereas we can't write constructor in interface.
• Interface contains methods that must be abstract; abstract class may contain concrete methods.
• Interface contains variables that must be static and final; abstract class may contain non-final and final variables.
• Interface can "extends" another interface, abstract class can "extends" another class and "implements" multiple interfaces.
• Interface is absolutely abstract; abstract class can be invoked if a main() exists.
• Interface is more flexible than abstract class because one class can only "extends" one super class, but "implements" multiple interfaces.
• Members in an interface are public by default; abstract class may contain non-public members.
• Interface is used to "implements"; whereas abstract class is used to "extends".
• Interface can be used to achieve multiple inheritance; abstract class can be used as a single inheritance.
[b]Abstract[/b]
It can be used with properties,classes,method,indexers and event.

An Abstract class can not be instantiated.
An Abstract class contains methods and accessors.
An Abstract class can not inherited.

[b]Interface[/b]

It contains only signature of delegates,method and events.
All members are public and abstract.
Interface is reference type.

[b]Sealed[/b]
It is applied for classes,methods and properties.

A Sealed class can not be inherited.
It throws an error if you sealed class as a base class

[b]Static[/b]

It is used for classes, methods,fields, properties, events, operators, and constructors.

All the members in the static class must be static.