UX is all about delivering something useful.
UI is all about delivering something beautiful.
Imagine a digital product as a cake.
What you first see is the icing, the shape, the decoration, and that’s the UI. It’s the presentation.
The inside of the cake is the UX. It’s the cake itself, how it tastes. It’s the core of the experience.
A cake would look naked without the icing (UI), and the icing has no purpose without the cake (UX).
The right combination of UX and UI leads to success!