UX, UI, IxD, CX: four disciplines people mix up all the time

A client regularly asks me to "redo the UX" of their site while actually pointing at the colors and the font. UX, UI, Interaction Design, Customer Experience: these are four distinct disciplines, and mixing them up gets expensive when a project gets scoped.

Take a streaming platform seeing a high drop-off rate at sign-up. Before jumping into a redesign, the first question isn't "how do we make it prettier," it's "do we actually understand where the problem sits." And that starts with a shared vocabulary.

Four words, four jobs

UX (User Experience) refers to a person's overall feeling before, during and after using a product or service. It's not a screen, it's a trajectory over time.

UI (User Interface) is the visible, interactive layer that enables action: typography, colors, components, interface states. It's what you see and touch.

IxD (Interaction Design) deals with how elements behave: transitions, the feedback given to the user, the logic of a gesture. It's the bridge between UX and UI.

CX (Customer Experience) covers every touchpoint a customer has with the brand, digital or not, across the whole lifecycle: the website, but also support, the invoice, the phone call.

Where UX comes from

UX's roots lie in ergonomics, cognitive psychology and human factors research from the 1960s. The term itself was popularized in the 1990s by Don Norman, then at Apple.

I invented the term because I thought human interface and usability were too narrow. I wanted to cover all aspects of a person's experience with a system.

Don Norman, quoted in several interviews on the origin of the term "User Experience"

Since then, UX has become a core discipline of digital design, on par with software engineering or product marketing. It doesn't replace UI: it comes before it and justifies it.

Roles and deliverables

The UX designer's role is to lead user research, model needs and test solutions. Their deliverables typically include personas, journeys, wireframes and prototypes.

The UI designer's role is to turn those findings into a coherent, accessible visual interface: high-fidelity mockups, component libraries, a design system. Both roles share the job of tracking tests and experience KPIs.

Who does what on a project

On a real project, these four disciplines rarely show up as separate roles: most often, one person (or a small team) owns both UX and UI, while keeping IxD in mind for micro-interactions and CX so as not to design a beautiful screen that's disconnected from a coherent customer experience.

What matters isn't rigidly separating roles at all costs, but knowing which level a problem sits at before trying to fix it. A high drop-off rate at sign-up is rarely a button-color problem.

Frequently asked questions

Are UX and UI really different, or is it just marketing?

It's a genuine professional distinction. UX handles structure and journey (does it work, is it clear), UI handles form (is it beautiful, consistent, accessible). You can have polished UI on top of broken UX, and vice versa.

Do you need separate UX and UI designers?

On a small project, one person can cover both if they're trained in both mindsets. On a larger project, separating the roles keeps good taste from masking an unresolved journey problem.

What does Interaction Design actually mean in practice?

It's the discipline that designs how an interface element behaves: what happens when you click, drag, hover. A poorly tuned transition or missing feedback is enough to make an otherwise "pretty" interface unpleasant to use.

Florent DABERNAT · Art director and founder of IDSEED, based in Aix-en-Provence. I help my clients with branding, UX/UI and web, using a clear and documented method. Learn more ➞