Comment by chii
The hickey definition is from the POV of the engineer - the creation of software with simplicity. Code that is simple, doesn't necessarily result in a piece of software that is simple for the end-user.
The tellman's version is for the end user - simplicity of use, by the user, with their existing expectation, culture and pre-knowledge. It's basically describing skeuomorphism in software (but not limited to just UI). It might be enormously complicated to create for the engineer, while it remains simple for the end-user.
if you think of the "end user" as the next person to work with the code, tellman's version is the ideal of encapsulation. some problem might be intrinsically hard to solve in terms of expressing it in code, but the end product could still be simple to work with given a properly encapsulated design