A proper UX design research for say designing a door would include all aspects of design to the point of calculating even the granular details that might effect it’s interaction/experience with the user. Whereas UI designer's job would be interpret and implement the defined aspects of that door in to a tangible/interactive form.
Sherjeel Javed

Walkthrough vs Coach marks

An incremental evolve from skuemorphic to flat/hybrid design ideology is a proof that an average smartphone user of today, is familiar with the basic idea of gestures, controls and behaviour. Creating opportunities for more minimal and to the point experiences..

When designing an app, it is paramount to devise a UX strategy which coincides with user’s comfort and familiarity. The idea is to design something that is intuitive, and translates in to an experience which has a minimal learning curve. This dictates as a basic rule of avoiding verbiage that might elude the user’s comfort zone. It is also a big reason why it is recommended to stick with the OS’s specific design guidelines when designing a native app. Walkthrough vs Coach marks