Both design terms are often misunderstood and hard to understand.
Let me help you to grasp it once and for all. User Interface (UI) is a product and User Experience (UX) is a process of using that product. Both, product (UI) and process-of-use (UX), are created by a designer. I will explain.
User is a person, you or me, who interacts with any digital interface, like mobile app, website, or computer software. That process of interaction is actual user experience. User is experiencing the use of a digital interface.
What is the difference between UX and UI? I will give an example.
Shoes are designed to serve you with comfort and looks. Shoes is a product, equivalent to UI. Your process of wearing those shoes is equivalent to UX. Another example would be Architecture. Interior Design you are living in is a final product (UI) while living in this product is a continuous process-of-use (UX). We can say that UI is a final product to be used while UX is a process of using it.
UI is part of UX. They are inseparable. Designing User Interface without User Experience is like leading an enterprise without a strategy. UI is always the final phase of UX design process.
UX/UI Design allows you to:
- set a bridge, an interface, between your enterprise and your user.
- discover your target market - who this interface is created for.
- define tasks of your interface - how successful user experience shall end.
- respond to your market competition - why user shall choose your interface.
- respect your enterprise goals - how interface fits into your overall business.
Personally, I tend to avoid using UX/UI terms. Instead I refer to my-professional-self as Interface Designer & Visual Developer, or Full Stack Designer, in order to avoid various misunderstanding.