UI is The abbreviation of User Interface.
UI is the part of a website or application that the user sees and pays more attention to the visual aspect of the issue.
The UI designer determines what each section should look like to give the website or application a good look. UI designer determines what each part should look like to make it more user-friendly.
UX is the abbreviation of User Experience, which means designing the user experience. It refers to the user's feelings and comfort while working with different site components and considers the aspects of user interaction with each section.