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.