@diggydog I don't think they are, except maybe as mods (for the PC). I've only played the first 3 challenges but the maps looked different from the main maps. Challenges are good for beginners but once you get good at completing the main maps, especially mod maps, they are far too easy in my opinion.
@8up-local as I'm console player, don't take my word for this, but having seen previous discussions on map creation, you may find that the challenge maps are there, just in a different folder, and it would just be a case of copying them over to a different directory or maybe you would need to open in an editor and add a couple of extra spawn points or similar to use as normal maps. Again, I stress, I'm making an educated guess here. I'm sure someone with proper modding/mapping experience would be able to clarify. If you're interested, might be worth asking the question in that sub-group.