Challenge Difficulty is set by the wiki-editors. It is used to give a rough idea of how difficult the challenge is to complete compared to others of the same level in a group. Group difficulty simply refers to how hard a challenge is to complete the primary object in a group - ignoring any star objectives.
Only options at the moment are:
- Easy: Easier than most of at the same level.
- Average: About the same as most at the same level.
- Difficult: More challenging than most.