Guix always seems like it has a cleaner well thought API, especially when reading the examples.
I'm guilty of not using Guix Home yet, though it is on my list (currently have a set up I like with org-mode and GNU Stow, not sure how to combine with this yet). I think the general idea is similar to the Guix system configuration where you declare what you want (using Guile) and then Guix Home puts everything where it needs to go in $HOME. This will keep previous copies (generations) to roll back to and should let you use the power of everything Guix/Guile to manage and generate them. But, as I've said, haven't yet dived int. Hope that is the general idea, but as someone that hasn't used Nix, can't compare them.