What i've found out...
is..
Basically Scandinavia is a region on the Scandinavian Peninsula in Northern Europe which includes Denmark, Norway and Sweden..
But it seems Scandinavia included counries where OLD NORSE was spoken!
And where the north germanic languages are now spoken.
Which is why those other nordic countries like Iceland and Finland were included as well!
Culturally and historically it included all these countries..due to the close relations Sweden had with all the countries.
So..it depends who you speak to..as to what Scandinavia really encompasses!
I guess, in a nutshell, it is really Norway, Sweden and Denmark but the NORDIC countries include Sweden, Norway and Denmark as well as Finland, Greenland Iceland and the Faroe Islands..
There you go...that's my understanding!
For what it's worth!