User Experience is a combination of tasks focused on optimization of a product for effective and enjoyable use. User Experience Design is the process of development and improvement of quality interaction between a user and all facets of a Product. User Experience Design is responsible for being hands on with the process of research, testing, development, content, and prototyping to test for quality results. User Experience Design is in theory a non-digital (cognitive science) practice, but used and defined predominantly by digital industries.
User interface design (UID) or user interface engineering is the design of websites, computers, appliances, machines, mobile communication devices, and software applications with the focus on the user's experience and interaction.