Any thoughts about the differences between interface and abstract class?

https://www.javatpoint.com/difference-between-abstract-class-and-interface

Another difference which is not mentioned in the article is that: Abstract class can be extended, which means it can have child class but it's necessary that child class must have a definition of abstract method present in the parent class. While on the other hand, interfaces cannot be extended which means that they don't have child classes. Interfaces are implemented by some classes.