Now this is confusing. From a couple of years ago Groundspeak said-
In our effort to inspire outdoor play through Geocaching, we are often faced with decisions about what to focus on next, and what to focus on less. It is through these decisions that we explore opportunities to grow the global game of geocaching.
Occasionally, during this process, we are faced with the reality that certain ideas don’t catch on as we had hoped. In these situations we owe it to ourselves and to you to make tough decisions about the future of every project and the resources to be applied to each. Sometimes, as a result, cool features must become casualties.
In this spirit, we have decided to retire Geocaching Challenges.
This means that, effective today, we have disabled the ability to create new Challenges. We have also removed the Challenges application from all mobile application stores. In approximately 7 days, we will be removing all traces of the Challenges functionality and related content from Geocaching.com.
Is there a difference from the challenge caches and what Groundspeak is talking about here? I have noticed a lot of challenge caches have been showing up here, most of them I'll never be able to accomplish as they are being placed by a couple of cachers with over 50,000 finds each.