Difference between Interface and Abstract Class

In many interviews you can face this basic question -What is the difference between the Interfaces and Abstract class and when we can use from both of them.

  

Interface	Abstract Class
If we don't know any thing about implementation just we have requirement specification then we should with Interface concept.	If we are talking for Implementation not completely Partially implementation then we should go for Abstract Class.
Inside Interface every method is always Public and Abstract whether we are not declaring or not. Hence Interface is also considered  as 100% pure abstract class.	Every Method in Abstract class need not be public and Abstract. In addition to abstract methods we can take concrete methods also.
We cannot declare interface method with the following modifiers. Private ,Protected final,static,synchronized,native and strictfp	There are no restrictions on Abstract class method modifiers.
Every variable present in interface is always Public , static and Final whether we are declaring or not.	The variables present inside the Abstract class need not to be public,static and final.
We cannot create object of Interface and because of that we cannot declare  interface variable with the following modifiers: private,protected,transient,volatile	There are no restrictions on Abstract class variable modifiers.
For Interface variable compulsory we should perform initialization at the time of declaration otherwise we will get the compile time error.	For Abstract class variable it is not required to perform initialization at the time of declaration.
In Interface Constuctor is not applicable	We can declare the Constructor in Abstract Class