What's the distinction? If a user is surprised by what happens when they interact with the UI, the UI has failed. If we're talking about an application that re

What's the distinction? If a user is surprised by what happens when they interact with the UI, the UI has failed. If we're talking about an application that requires a lot of outside knowledge (e.g. GIS (Geographic Information Systems (mapping)), accounting, video editing), you're not going to be able to "teach" the user what they need to know in the UI or some short videos. In one case on-boarding is a symptom of a bad UI, in the other it's more-or-less useless.