Simon Guest (@simonguest) has a great post on the differences between UI and UX, illustrated through real world design.
Years ago, I noticed that the vernacular nomenclature around product development had shifted from UI to UX, but I never really paid much mind to what the (perceived) differences were between the two.
UX feels a bit more self-important, so I figured it was a differentiating word change only, like the switch from expert to guru to ninja, cosmetic only.
Simon’s examples illustrate very plainly the differences. So, now I’m feeling edified and bit sheepish.