What is the deference between abstract class and interface ???

Answer 1

Abstract class: is a restricted class that cannot be used to create objects (to access it, it must be inherited from another class).
https://www.w3schools.com/cs/cs_abstract.asp

An interface is a completely "abstract class", which can only contain abstract methods and properties (*with empty bodies*)
https://www.w3schools.com/cs/cs_interface.asp