What is the difference between OnChanges and DoCheck in Angular 2?

Question

Difference between them seems to be very confusing to me. What is difference between them and exactly when they are called

Answer 1

First of all Kudos to the above answers. I am adding a use-case for both of the functions which I have faced personally.

ngOnChanges() (OnChanges): to detect changes for variables passed by value

ngDoCheck() (DoCheck) : to detect changes for variable passed by reference such as arrays, which are not detected by ngOnChanges() as the old value and the new value have the same reference