In regards to the differences between usability and user experience, actually, in IT world there are big differences between the two. Briefly, most efforts used to focus on usability matters in the early days of IT design and development. Later, it was understood that usability is not sufficient to address what users expect from a system or device, and user experience (UX), which covers broader aspects of users' interaction with the product and services, started to be employed. UX usually deals with design aspects like satisfaction, meaning, pleasure, and the value generated in relation to the product/services. Here is a good introduction to the UX and UX design: https://www.interaction-design.org/literature/book/the-encyclopedia-of-human-computer-interaction-2nd-ed/user-experience-and-experience-design

Hope this helps

 Dear Baki

Thank you. This is really helpful. I can see the difference now. Are there any measures or scales available in this area?

Regards

Farooq

Thank you David. This is helpful

You might also be interested in the System Usability Scale (SUS). This is a 10-item scale that is widely used. http://www.usability.gov/how-to-and-tools/methods/system-usability-scale.html

Thank you Rebecca. This seems to be perfect choice.

Regards