Oops Concepts in C#

Question

I have little bit confusion about oops concept.... In oops ,we have 4 features,

 

1.Abstraction

2.Encapsulation

3.Inheritance

4.Polymorphism

 The above 4 features are 4 fillers to the  object oriented programming.

--->Is there any difference between Abstraction and Abstract classes,if yes then What is the difference between Abstraction and Abstract classes.

 

--->Is there any chance to differentiate Abstraction Vs Inheritance??

 

Main advantage of Inheritance is 'Reusability' as well as we can use Abstraction for the same purpose

 

Can any one clear my confusion??