What is the main difference between creating an object of a class and extending a class.In both the cases we can use the methods and properties of the class which is been extended or made an object

In reply to gordon:

Thanks Gordan

I know about the extended classes . What I am asking here is the difference while using when we make an extended class and when we make an object of the class?
We are deviating here from original Question. I can’t find explanation in the first comment you have answered.