It’s a pretty regular debate for us, here in the Black Swan Creative team. What is UX anyway? A little like Justice Stewart and his observation on obscenity, we know it when we see it, but an exact definition eludes us. The boundaries between UI design and UX design are incorrigibly blurred and seem to change while we’re not looking.

And we’re not alone. It’s a common question on design forums and plenty of authors have attempted to answer the question: what is the difference between UI and UX? The answers tend to be long and listy: lists of things that UX and UI designers do or make. Persona research, interaction design, wireframes, user journeys, sitemaps (but isn’t that IA?) … it all ends up in Venn diagram hell:

Adapted from The Disciplines of User Experience Design by Dan Saffer

A Simpler Definition

Reducing UI and UX roles to their constituent tasks and sub-tasks can be useful for designers who need a detailed rundown of responsibilities but it doesn’t help an outsider get a pithy sense of the distinction. We prefer to start with a more granular philosophy: space versus time.


UI is about Space


UI design deals with what’s on the screen at any one time, how those things are laid out and how a user achieves tasks at the lowest level of detail by interacting with elements in the screen’s space.


UX is about Time


Time at different scales. On the short timescale, it’s about arranging sequences of interactions to help users achieve their goals. In the longer term it’s about ongoing engagement with a service, across multiple sessions, through multiple channels.


It’s Not a Perfect Distinction

There’s obviously overlap between these two. When you open a dropdown, that’s a sequence, an interaction in both space and time. And a user experience can be dramatically affected by the choice of navigation controls, for example. But as a top-level distinction it gives you a surprising amount of mileage, particularly as a quick water-cooler explanation to a non-designer. The two concepts are as basic as you could hope for, requiring no further explanation.

And the Venn diagram is much easier to deal with – just two circles.


Ross strives to call himself an interaction designer but he’s swimming against the tide; everyone else calls him the UX guy. It doesn’t really matter, he just carries on thinking about how to make software that’s great to use.