I assume he went through “Submit a new story” on the left
If you try submitting yourself, you’ll see that you are asked to select from the existing list of challenges - you don’t have detail description about any in this editor, so you go with what sounds reasonable. (Hacking Utopia is the only challenge that has OpenCare name in it, so my guess is that’s why he chose it).
Then you are asked to assign your post to some key topics - which are channels.
So Challenges contain questions you are trying to answer; whereas Channels are general topics in the the whole website… They will end up structuring the conversation in complementary ways, and we can then create pages based on grouping stories according to channel too - it adds another layer of understanding quicklier what people are talking about. For example have a look at this (in progress): https://edgeryders.eu/en/content/channels