I would say it is slightly less than bluing....
I don't see a lot of difference.
But I think the way to approach the finish on a firearm of the character that I shoot, is that neither the bluing, nor the case hardening is intended to provide prootection.
Clean it thoroughly as quickly after shooting as you can manage. Use oil and/or another surface protectant to protect the finish.
My reading of history convinces me that most bad government results from too much government. Thomas Jefferson