But UX is bigger than UI. Good UX might simplify some use case so that user might not need to see any UI at all.
When I was at university, I attended a UI class which - although in the CS department - was taught by a senior psychologist. Here, the premise was very much on how to design interfaces in such a way that the user can intuitively operate a system with minimal error. That is, the design should enable the user to work with the system optimally.
I only heard the term UX much later, and when I first became aware of it, it seemed to be much less about designing for use and more about designing for feel. That is, the user should walk away from a system saying "that was quite enjoyable".
And these two concepts are, of course, not entirely orthogonal. For instance, you can hardly enjoy using a system when you just don't seem to get the damn thing to do what you want. But they still have different focuses.
If I had to put in a nutshell how I conceptualize the two disciplines, it would be "UI: psychology; UX: graphics design".
And of course such a simplification will create an outcry if you're conceptualization is completely different. But that just takes us back to my very first sentence: not well-defined names are open to interpretation.
> Here, the premise was very much on how to design interfaces in such a way that the user can intuitively operate a system with minimal error.
Yes, that's a good default goal for most software, but not always appropriate.
Eg for safety critical equipment to be used only by trained professionals (think airplane controls or nuclear power plant controls) you'd put a lot more emphasis on 'minimal error' than on 'intuitive'.
We can also learn a lot from how games interact with their users. Most games want their interface to be a joy to use and easy to learn. So they are good example for what you normally want to do!
But for some select few having a clunky interface is part of the point. 'Her Story' might be an interesting example of that: the game has you searching through a video database, and it's only a game, because that search feature is horribly broken.
UX is just a weaselly sales term, "Our product is not some mere (sneers) interface, no, over here it is a whole experience, you want an experience don't you?"
I found a paper that was definitely taking the perspective that the "user interface" encompasses all the ways in which the user can accomplish something via the software. It rated the effectiveness of a user interface in terms of the time taken to complete various specific tasks. (While remarking that other metrics matter to the concept too, and also measuring user satisfaction and error rates.)
But that paper also suggested how the term might have specialized - four pieces of software were studied, and they are presented in a table that gives their "interface technology", in two cases a "character-based interface" and in the other two a "graphical user interface".
Enough usage like that and you can see how "interface" might come to mean "what the user interacts with" as opposed to "how tasks are performed".
( https://www.nngroup.com/articles/iterative-design/ . It really is dated 1993, which I made a point of checking because Google assigns the "date" of a search result based on textual analysis, and it is frequently very badly wrong. I can't really slam the approach, which I assume was necessary to get the right answer here, but the implementation isn't working.)
It's just the euphemism treadmill. Just like people perennially come up with new technical terms for the not-so-smart that are meant to be just technically and inoffensive, and over time they always become offensive, so someone has to come up with new technical terms.
See eg https://en.wikipedia.org/wiki/Idiot
> 'Idiot' was formerly a technical term in legal and psychiatric contexts for some kinds of profound intellectual disability where the mental age is two years or less, and the person cannot guard themself against common physical dangers. The term was gradually replaced by 'profound mental retardation', which has since been replaced by other terms.[1] Along with terms like moron, imbecile, retard and cretin, its use to describe people with mental disabilities is considered archaic and offensive.[2]
Yeah, just look at Windows {10,11} and Android. They simplified so much that it's unusable.