They are both text based configuration file formats made to be easier for humans to interact with, so I'm not sure what you're confused about?
That’s about the least interesting thing about Dhall. (It’s weird that they tout it prominently on the homepage.) There are so many flavors of syntax sugar for JSON, Dhall is a completely different beast.
You might want to ask the HN admins to rename the title for this post, then.
It looks fine to me. Reducing repetition is precisely the type of thing Dhall’s features should be useful for.