It is important enough to know that usability != user experience.
But how are they different?
Jared Spool thinks usability is about achieving the goal while user experience is about whether the process is delightful.
McNamara and Kirakowski consider usability as an issue of the interaction between the user and the product, while user experience includes ‘the wider relationship between the product and the user’ and ‘the individual’s experience of using it’.
So, let’s try filling out a 2×2 matrix, see if it makes sense to you or other people. Comment if you disagree.