Swedish vs Scandinavian

Swedish and Scandinavian both are nouns.

Word	Noun	Adjective	Verb	Adverb
Swedish	Yes	Yes	No	No
Scandinavian	Yes	Yes	No	No

As nouns, Scandinavian is a hypernym of Swedish; that is, Scandinavian is a word with a broader meaning than Swedish:

Swedish: a Scandinavian language that is the official language of Sweden and one of two official languages of Finland
Scandinavian: the northern family of Germanic languages that are spoken in Scandinavia and Iceland

Other hypernyms of Swedish include Nordic, Norse, North Germanic, North Germanic language, Scandinavian language.

Swedish (noun)	Scandinavian (noun)
a Scandinavian language that is the official language of Sweden and one of two official languages of Finland	the northern family of Germanic languages that are spoken in Scandinavia and Iceland
	an inhabitant of Scandinavia

Swedish (adjective)	Scandinavian (adjective)
of or relating to or characteristic of Sweden or its people or culture or language	of or relating to Scandinavia or its peoples or cultures