Focuses on understanding user behaviors, needs, and motivations through observations, task analysis, and other feedbacks.
It is the approach for a digital product which ensures that the UX vision is aligned by focusing on solving the right problems for target users.
A user interface is essentially the features of a device or an application that allow a user to interact with it smoothly and intuitively.
It typically consists of evaluating a product by testing it with your target users and optimizing it.