Despite the fact that these two concepts are closely related, overlap and rarely exist without each other, there is a certain difference between them.
UI development is the creation of interface that provides the best, simple, fun, and not burdening way of user interaction with the product. Most of the work during the creation of the interface is the observation of user behavior, allowing you to make decisions based on the collected data.
UX is the interaction itself. It is the intangible design, strategy development, which leads us to the solution. This term denotes the full set of interactions that begins before the user will use your product, and continued much later.
Thus, User Experience and User Interface are equally important but UX does not equal UI. While the UI is a point of interaction, UX is the interaction itself.
UX encompasses all that we call experience. UX covers satisfaction of user needs, creating a comfortable environment for users when they use your service. While UI main concern is only visual design. UI is the tool by which the user interacts with the product. It is a mean of communication.
In a broad sense UI is what the user see while looking at your site, UX is how they feel. Both are incredibly important because their interaction will affect the work of website for the company and for the customer.
UI can be interpreted as an input allowing to control the system.
UX can be interpreted as an output allowing the system to demonstrate the effect produced by the user’s manipulation.
There is something that unites these concepts. Both UX and UI are aimed for users. They They should work together to achieve the ultimate goal: to make a user interested in a product or give them certain information.
UX and UI do not separated from each other. The UX process does not end when UI has been implemented. It is a cycle which needs to be repeated to re-evaluate the user’s experience and to fix the system using new obtained data.