Most difficult thing: Perceptions of how to manage people.
Depending on how a person sees their role as a manager/executive can determine how they manage others.
It is a challenge for some managers to manage without being overly bossy or aggressive.
It is a challenge for some managers not to be too friendly, thereby making it difficult to handle difficult situations.
Funnily enough, the work executive seems to give a slightly more acceptable name for a manager as you don't immediately think of a manager but someone who is delegating work to others.