The USA is still one of the very few countries that doesn’t enforce the French varietal naming convention — especially “Champagne.”
They are stepping up their efforts — the last 3 or 4 flights I have been on have had small cards with the meal (I am a frequent flier and usually fly 1st Class) that whine (IMHO) about calling sparkling wines (Brut to the rest of the world outside of Champagne) “Champagne.”
There are other distinctions (”fermented in the bottle vs. fermented in this bottle”) but I am sure everyone knows of what I speak.
Actually, Brut means it's on the drier end of the sweetness scale. It is not a designation for a wine as such.