# **1. Abstraction**

Abstraction is one of the most powerful features of object-oriented programming. It is a way to provide users with only the most relevant and essential information​​ while hiding the rest.

**Abstract classes** don't provide complete abstraction -- they can have concrete methods along with the abstract ones.

**Interfaces** provide complete abstraction; however, they can not have concrete methods.

# 2. Constructors

A constructor is the special method of a class ​used to initialize the objects of the class.

**Abstract classes** can have different types of constructors.

# 3. Multiple inheritance

Inheritance is another feature of object-oriented programming where a particular class can derive from a base class. Multiple inheritance allows the extension of more than one base class in a derived class.


**Abstract classes** do not support multiple inheritance.

**Interfaces** support multiple inheritance.

Abstract class vs. Interface in C#

Abstract classes offer partial abstraction with concrete methods and support constructors but not multiple inheritance. Interfaces provide full abstraction, no constructors, and support multiple inheritance.