UX vs UI: what's the difference?
UX is how it works and feels to use; UI is how it looks and what you touch. You need both, and they're not the same job.
UX (user experience) and UI (user interface) get used interchangeably, but they’re different things, and a product needs both to be done well.
UX: how it works
User experience is the whole journey: can someone find what they need, understand it, and get it done without friction or confusion? It’s structure, flow, logic and clarity. Good UX is mostly invisible. You only notice it when it’s missing and something feels harder than it should.
UI: how it looks
User interface is the visible, tangible layer: the buttons, colours, type, spacing and states, everything you look at and touch. Good UI is clear, consistent and on brand, and makes the right action obvious.
A simple way to hold it
UX is the plan of the house; UI is the décor and the door handles.
A beautiful interface over a confusing experience frustrates people. A logical experience with a careless interface feels cheap and untrustworthy. The two have to be designed together (alongside accessibility and typography), which is exactly why it helps to work with someone who holds all of it at once.