After web site accessibility, “user experience” (abbreviated as UX) is probably the phrase that most people tend to confuse usability with. While the topic of the difference between usability and user experience has been discussed by various experts in the respective fields, I feel the need to write about it for two main reasons. The first reason is that several posts I have encountered emphasize the distinction between these two terms, yet they fail to highlight the relationship that exists between usability and user experience. The second reason is that whilst most of the posts are similar in nature, I have found some minor, albeit very valid points scattered in various posts I have read. Therefore, the objective of this post is to discuss these two terms, whilst highlighting their differences and more importantly the relationship that exists between them in a clear, concise way.
The difference between usability and user experience
- ISO Definition: Usability is concerned with the “effectiveness, efficiency and satisfaction with which specified users achieve specified goals in particular environments” (ISO 9241-11)  whilst user experience is concerned with “all aspects of the user’s experience when interacting with the product, service, environment or facility” (ISO 9241-210) .
- Aim: In terms of a web site, the aim of usability is to make that web site easy to use whilst the aim of user experience is to make the user happy before, during and after using that web site. Thus, usability relates to the ease with which users can achieve their goals while interacting with a web site while user experience is concerned with the way users perceive their interaction with that web site 
- Defined as a Question: Usability can be modeled as the question “Can the user accomplish their goal?” whilst user experience can be phrased as “Did the user have as delightful an experience as possible?” .
- Resources Required: Usability involves those employees who influence the user interface design of a web site whilst user experience requires the collective and seamless effort of employees from various departments including engineering, marketing, graphical and industrial design and interface design .
- 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” 
- Effect on User Interface: A usable user interface is one which is typically intuitive, simple or extremely learnable. A user interface whose aim is to create a positive user experience is one which is pleasing to the user. This does not mean that when the focus is on user experience, the user interface is not usable. To the contrary, user experience professionals typically hand over their designs to usability professionals so that they can validate them .
The relationship between usability and user experience
Usability is a narrower concept than user experience since it only focuses on goal achievement when using a web site. By contrast, user experience is a “consequence of the presentation, functionality, system performance, interactive behaviour, and assistive capabilities of the interactive system” . This essentially means that user experience includes aspects such as human factors, design, ergonomics, HCI, accessibility, marketing as well as usability. An alternative way to look at this relationship is by subdividing user experience into utility, usability, desirability and brand experience. This is best illustrated by representing these sub divisions as concentric circles where the innermost circle is the most basic aspect of user experience as shown in the diagram below:
- International Organisation for Standardisation, 1998. ISO9241 Ergonomic, Part 11: Guidance on usability. Geneva, Switzerland.
- Stewart, T., 2008. Usability or user experience – what’s the difference ? [Online] Available at: http://econsultancy.com/uk/blog/2321-usability-or-user-experience-what-s-the-difference?utm_campaign=Skimlinks&utm_medium=affiliate&utm_source=cj
- UXgru, 2010. The Difference between Usability and User Experience [Online] Available at: http://www.uxrevisions.com/user-experience-design/the-difference-between-usability-and-user-experience/18/
- Spool, J., 2007. The Difference between Usability and User Experience [Online] Available at: http://www.uie.com/brainsparks/2007/03/16/the-difference-between-usability-and-user-experience/
- Owen, R.J., 2010. The Differences between Usability and User Experience [Online] Available at: http://www.developria.com/2010/01/the-difference-between-usabili.html
- Baekdal, T., 2006. The Battle Between Usability and User-Experience [Online] Available at: http://www.baekdal.com/articles/usabilty-vs-user-experience-battle
- Nielsen Norman Group, 2007. User Experience – Our Definition [Online] Available at: http://www.nngroup.com/about/userexperience.html