llano vs champaign

llano and champaign both are nouns.

Word	Noun	Adjective	Verb	Adverb
llano	Yes	No	No	No
champaign	Yes	No	No	No

As nouns, champaign is a hypernym of llano; that is, champaign is a word with a broader meaning than llano:

llano: an extensive grassy and nearly treeless plain (especially in Latin America)
champaign: extensive tract of level open land

Other hypernyms of llano include field, plain.

llano (noun)	champaign (noun)
an extensive grassy and nearly treeless plain (especially in Latin America)	extensive tract of level open land