chateau vs country house

chateau and country house both are nouns.

Word	Noun	Adjective	Verb	Adverb
chateau	Yes	No	No	No
country house	Yes	No	No	No

As nouns, country house is a hypernym of chateau; that is, country house is a word with a broader meaning than chateau:

chateau: an impressive country house (or castle) in France
country house: a house (usually large and impressive) on an estate in the country

chateau (noun)	country house (noun)
an impressive country house (or castle) in France	a house (usually large and impressive) on an estate in the country