There’s definitely a difference between usability and UX design. In some ways it’s very clear in other ways it’s not. This is a good article that attempts to note the differences. Be sure to scan the replies.
Impact: Although user experience requires more effort to do well, its results have a better impact . When done properly, user experience effectively enhances the relationship between the user and the brand. This is because “true user experience goes far beyond giving customers what they say they want, or providing checklist features”