UX is the flow
User experience is the logic: who uses this, what do they need, and what's the shortest path between the two? UX work is research, flows and wireframes. You can't see good UX — you feel it as the absence of friction.
UI is the look and feel
User interface is the surface: type, colour, spacing, components, states. UI makes the flow beautiful and legible. A product can have good UX and bad UI — usable, but ugly — or the reverse: gorgeous screens that confuse everyone.
Web design is both, plus the build
Web design takes the UX and UI and turns them into a working website: the pages, the performance, the mobile behaviour, the contact form that actually delivers. When someone says “I need a website”, this is usually what they mean — design and build together.
When you need which
Building a product — an app, a tool, a platform? You need UX and UI, and usually a team to build from the files. Need a site that sells your business? You need web design, which includes the UX and UI thinking for that site. The question isn't which discipline is better; it's which job you're actually hiring for.
What each one costs you when skipped
Skip UX and you pay in rebuilds: screens that look finished but confuse users, flows that need rethinking after launch, features nobody finds. Skip UI and you pay in distrust: a product that works but looks unfinished makes people assume the whole thing is unfinished.
Skip the build — the web design step — and you pay in mockups: beautiful screens that never become a website, because nobody owned the performance, the mobile behaviour, or the form that delivers the enquiry. Each discipline covers a failure the others can't see.
The practical rule: if it lives on the web and needs to convert, hire web design and make sure UX and UI thinking are inside it. If it lives as a product people use daily, hire product design — UX and UI as the job itself — and keep a build team beside it.
If you're still unsure which you need, describe the job in one sentence — “a website that sells” or “a product people use daily” — and the answer usually names itself.
How the three work together on one project
Take a landing page project. UX maps it first: who arrives, what they need, what action they take, in what order. UI designs it: the screens, the type, the hierarchy, the states. Web design builds it: performance, mobile behaviour, the form that delivers the enquiry. Three jobs, one page, in that order.
Take an app project and the shape changes: UX and UI become the whole job, and the build team takes the files. The disciplines don't compete — they hand off. The expensive mistakes happen when a project hires one discipline and expects it to do all three.
Related service: UI/UX Design.