what's the exact difference between the Sprint Goal and the increment?

Have you read the Scrum Guide? There are sections on each of these.

The Sprint Goal provides guidance to the Development Team on why it is building the Increment. The Increment is a mutable artifact which can be inspected and adapted, the Sprint Goal is not.

@Ian Thanks for your answer,

I got confused because sometimes it seems that the sprint goal will be the "increment" at the end of the sprint. Do you have any example of a craft spring goal and an increment ?. So that I can see the difference?

and yes, I did read the scrum guide but as you know it's difficult to master ;)

Thank again,

A Sprint Goal might be to create a shopping cart. The increment might have functionality to add, remove, and list items, to see the total cost of items, and the ability to proceed to check-out.

@Ian Thank you for your response, it has been a great help to me to understand the difference

I would venture to say that the Sprint Goal is the map you use when planning a road trip (guidance) and the completion of the trip is the increment (the tangible work you completed). 

As per my understanding, each item of a product goal/Sprint goal will be called as increment when it meets the definition of done.