Looking at the [UX principles](http://uxmag.com/articles/quantifying-usability) that mozilla use as [keywords to tag bugs in bugzilla](https://bugzilla.mozilla.org/describekeywords.cgi#ux-affordance) it looks like [ux-affordance](https://bugzilla.mozilla.org/buglist.cgi?keywords=ux-affordance) and [ux-discovery](https://bugzilla.mozilla.org/buglist.cgi?keywords=ux-discovery) are very similar:

> 
> ux-affordance — controls should visually express how the user should
>  interact with them. [Source: Norman] 
> 
> 
> ux-discovery — users should be able to discover functionality and
>  information by visually exploring the interface, they should not be
>  forced to recall information from memory. (This is often the nemesis
>  of ux-minimalism since additional visible items diminish the relative
>  visibility of other items being displayed). [Source: Nielsen]
> 
> 
> 

Are these just two ways of looking at the same problem, or are there UX issues that would fall under one principle but not the other?

**Update:**

Perhaps the tag-wiki definitions on this site could be updated based on the responses to this question. They are currently:

> 
> Affordance is a property of an object that naturally indicates how the object can be used.
> 
> 
> 

And for discovery:

> 
> the process by which a user learns what a program can do through affordances in the UX.
> 
> 
>