It is customary to characterise individual administrative bodies as ‘courts’ because they have certain similar characteristics. They are formerly classed as administrative bodies, but are organised and consider cases along the lines of courts of justice.
Such bodies are tasked with resolving legal disputes and their rulings are legally binding. They have a significant degree of independence in their undertakings in relation to other (higher) administrative bodies. Their rulings can be tried by the ordinary courts, however.
A characteristic of such a special court is that it only considers certain types of cases that are not usually considered by the ordinary courts.
See this page in "bokmål" to get a list of such courts.