According to what I found online
Celtic Sea Salt® is a Brand name registered since 1976
You could apply that name to anything and it doesn't mean anything
If you've ever seen Chicken of the sea on sale you'll know it has nothing to do with Chicken and is infact a brand of Tuna Fish.
Personally I have experimented with numerous salts and from what I can determine the most important factor was where it came from and how it was treated.
I personally prefer Salt that comes from the living sea that we have with us right now, not the salt that came from 10,000+ years ago such as rock salt, pink salt, etc
I also believe the way the salt is dried is important. I've seen more health benefits from salt that was hand collected and air / sun dried then those salts that were dried in a machine
If it doesn't say on the box it was hand collected, hand harvested, dried in the sun or air then it probably wasn't.