A UX designer is more of a creatively driven person who can reproduce the vision of a website through his codes and a sense of creativity thereby creating a user experience meant for the target audience.
While maintaining the aesthetic beauty of the UI, the designer also has to take care the structure and the flow of the website so that the user does not have any issues with navigating through the website.
User experience is a broad term encompassing everything it takes to create an experience that a user would achieve while going through the user interface. The appearance of the website, ease of navigation, placing of strategic links, structure and flow are the factors that need to be taken along while on a journey to create a magnificent user experience.
A UX designer has the responsibility of taking care of all these elements together. A UX designer may not be a master of one, but must be a jack of all trades as an enterprise with a smaller workforce might not provide for a separate designer, analyst, and architect.