What is the difference between incapsulation, constructor and abstraction in c++?

Answer 1

Abstraction is an OOP concept that focuses only on relevant data of an object. It hides the background details and emphasizes the essential data points for reducing the complexity and increase efficiency.
Encapsulation is a method of making a complex system easier to handle for end users. The user need not worry about internal details and complexities of the system. Encapsulation is a process of wrapping the data and the code, that operate on the data into a single entity.
C++ constructor is used to initializing the member variables of an instance of a class that is the object of a class. 

Answer 2

Once search on Google u will understood much better
https://www.quora.com/What-is-the-difference-between-abstraction-and-encapsulation-2