UI stands for User Interface Design. In fact, UI design is a part of the website or application that the user sees and deals more with graphic aspect of the subject. Designer of the UI, determines what the appearance of each section should be in order to give a proper effect to the website.
User interface design is implemented with the help of site graphists and Front-end programmers. User interface design is important because the user has a direct relationship with it, and people tend to trust websites with poor UI less.
UX stands for User Experience Design. It refers to the feelings and comfort of the user while working with various parts of the website and considers aspects of user’s interaction with each section. That our website is designed in such a way that each section is easily accessible to users and that the ease and comfort of the user are considered for working with each section, are issues of UX design.
Needless to say, this was just an aspect of UX design. Its second aspect is related to user guidance. It means how to direct users of a page to their desired page and how users pursue our goals on the website. In fact, the second dimension of user experience refers to the management and guidance of the user from the moment of entering the site to the moment of purchasing the product (or any other purpose).