This is why I always give both the language AND country code when referring to a language. There are too many standards, a fact illustrated by the fact that even standards needs
best practices (as in IETF BCP 47).
Then things become immediatly clear:
The same language spoken in 2 countries (Or as Wild put it: "Two countries separated by a common language"):
- en-US is American English
- en-GB is British English
One country with two languages:
- nl-BE is Dutch spoken in Belgium (sometimes referred to as Flemish)
- wa-BE is Walon, a dialect from French spoken in Belgium
And for the Norwegian case:
- nn-NO is NyNorsk
- nb-NO is Borkmal (Couldn't find the accents, sorry)
- se-NO is Norga (North Sami)
This basically covers about 90 % of all languages.