And it's awesome. The staff have to actually study and pass a test so they can advise on wine selection. The selection is huge and far beyond what's visible in the stores - and there's a great app for ordering stuff. They even have massively subsidised wine courses and a free wine magazine that's surprisingly good.
It isn't terribly different in practice from state and local regulations in the US, except the rules in Norway are the same nationwide.
For example, where I live in Ohio, I can buy beer at the grocery store with some restrictions on Sundays. I can also buy harder liquor in the state store, which is located in a physically separated section of the grocery store and where you have to be 21 (legal drinking age) to shop. Alcohol is subject to special taxes here, as well.
In Norway I would buy beer at the grocery store then go across the street to Vinmonopolet and buy some wine. I could do that at age 18, though some harder liquor is/was restricted to 21.
So it's not all that different, except in the US the limits are a little different, it's more likely to be regulated at a local level, and typically run by some private for-profit entity.
Certain parts of the US (typically further southeast) anything over like 5% is exclusively in ABC Stores, a completely separate building and company from grocery stores.