Siouan language vs Siouan

Siouan language and Siouan both are nouns.

Word	Noun	Adjective	Verb	Adverb
Siouan language	Yes	No	No	No
Siouan	Yes	Yes	No	No

As nouns, Siouan language and Siouan are synonyms defined as:

Siouan language and Siouan: a family of North American Indian languages spoken by the Sioux

Siouan language (noun)	Siouan (noun)
a family of North American Indian languages spoken by the Sioux	a family of North American Indian languages spoken by the Sioux
	a member of a group of North American Indian peoples who spoke a Siouan language and who ranged from Lake Michigan to the Rocky Mountains

Siouan language (adjective)	Siouan (adjective)
	of or relating to the Sioux people or their language and culture